Here are two additional videos which supplement this nicely, hope everyone's having a great day! When To Shift For The Best Acceleration - ua-cam.com/video/zZBqb0ZJSwU/v-deo.html LSPI: Don't Lug Your Engine - ua-cam.com/video/soJea7xEt-8/v-deo.html
Does this also apply to diesels, since there are presumably no pumping losses across the throttle plate to worry about, and where one needs to get the turbo spinning to get efficiency?
Engineering Explained - Thanks for the next link. I am a 31 year old Mom that just got her license last year - had a huge fear of driving - and now I've been doing research because when I started driving I had a Jetta and I taught myself to drive in her. My next car, a Monti Carlo (did I spell that right lol) wasn't a manual and I hated it. She has problems with the transmission wasn't changing gears fast enough imo, and then she overheated and it went down hill from there. She's currently in the shop. My Jetta long gone by this point. So my Wife surprised me with a manual 95 Jeep YJ, she needs work done to her. Cosmentic and a few things under her Hood but for the most part she's perfect imo. Point of this comment is I've been watching a lot of your videos so I can tinker myself on the Jeep. And even though I taught myself to drive the Jetta, I don't know all the right ways, seeing as I know just because I can get it moving doesn't mean I'm doing everything right in the long run. Lol. So thanks for these types of videos! I need to get better at changing gears at the right time. With this video I now believe I have been changing gears just a bit too late in the Jeep. She's older than the Jetta was and I have to get used to how she ticks. Thanks for the help! :-)
The thing is, the bsfc maps are created at "steady state" conditions, which is close to what you show in the constant speed test. But acceleration is a "transient" condition, so how can you know where you are on the map?
Some years ago, I recall BMW saying that for the best volumetric efficiency, they recommended flooring the throttle in every gear - and shifting at 1500rpm. This is probably a little extreme, but the principle is the same. I've used this technique on long road trips in an '01 Focus ZX3 (so I generally shifted at 2000 rpm to avoid lugging - it was not exactly a torque monster.) I achieved an average of 35 mpg, at an average speed (including stopping for fuel) of 65mph. All by using the maximum throttle opening I could use for the speed I wanted to do, and sticking to the highest gear I could get away with.
The rotary actually gets better mileage at (somewhat) higher RPM and lower load (throttle opening). At 35 mph uphill, if I use 6th gear it takes a lot of throttle (around 1500 rpm) to maintain speed and the mpg goes down to 6-9. In 4th gear, it's loafing along at 2500 rpm or so, and the mpg is at least double that. For a light car (weighs the same as a Civic), there's a really big mpg difference between uphill and level. The rule for a rotary seems to be the opposite of a piston: use whatever gear you need the least throttle to get the amount of power you want. Generally 2500 - 3200 rpm seems to give the best mileage. Above 3250, the SSV valve activates (it switches to the high-rev intake tuning) and above 4000, the 5th and 6th fuel injectors operate. FYI: at 60 mpg on level ground without wind in 6th, I get around 28-32 mpg. I did an experiment, and drove it like a Honda for a week, about half city and half highway, and got 23.4 mpg for the week. Driving a little "enthusiastically" and completely city driving (lots of sitting in traffic) brings it down to 18-19 mpg. It's a completely different beast.
Jack Vinall mine gets up there too when I’m on the highway but you cover more distance without stop lights and constant shifting through gears. So it works out to be just as efficient
I always start from 2nd gear I only first gear if im on an incline As far as shifting , I just keep my rpms as low as 1500 to 2krpms since my car has enough torque to get it moving If you're driving a car with weak torque, then you need higher rpm (a honda civic for example) vs a car with high torque (a camaro for example)
Yes, this is a highly detailed, well presented (a little long winded) explanation. Here's the short version; shift at as low an rpm as you can without lugging the engine. Once you've done this a few times it will become second nature to you.
Exactly. I'm always Driving between 1.5k - 2k RPMs with my 306 GTi, but without lugging the engine. It doesn't matter how higher revs are efficient, 2k RPM is always half of 4k RPM, so it will burn fuel slowly.
@@mryan4452 However, not accelerating hashly does not mean that you shouldn't go full throttle. Some people might think that much throttle means much fuel.
In a diesel car such as mine with 3.0L This is me. Everytime I change gear the only RPM where it can still move without having a vibration is more than 1.5k lower than that. It'll start to vibrate itself which isn't that great. The lower the gear the higher RPM is the time when you change your gear. As for me 1st would be around 2.2 Same goes to 2nd and 3rd 4th would be 1.8RPM All of this are the RPM when I change my gear. It'll go back to 1.5RPM which is the best spot for me. Different cars may have different RPM when to change gear. After using your car a lot of time you'll eventually know when you'll change your gear in the most efficient way possible
Very good explanation, great shifting is acquired by feel. Feel of the vehicle with feel of the road. Generally the heavier vehicles will require higher RMP's. The automatic transmission was invented for women drivers that demonstrated the lack of feel for such machines...
Engineering Explained thanks Jason for confirming my suspicions of a newer manual 7 or 6 speed is way more gas conservative ( @ 60mph~ ) vs a 3 speed non locking 60s automatic transmission I found that one by accident using a turbocharger calculator and reading about other peoples builds getting better mpgs I’m only part of the way through my build changes so I’m not to where I can data log and test everything 😏
Engineering Explained off topic but as video suggestion how much would you need / calculating for parking lot A/C or heating to work with only a battery? I tried finding it but to no avail I do have numbers for how much all of the equipment can consume @ full load in kWh but that’s different from “ just maintaining temperature deltas “ aka outside is 110F and I’m asking for less than 75F inside the car and by the way this might be a good companion video to tobitda Vinci video on Tesla model 3 battery packs specifically is it more efficient use seat heaters ( Peltier device type and efficiencies ? ) or the main cabin heat exchangers for heating / cooling or a “ cool shirt “ with a ice chest and water Plus which is faster for the job?
Many petrolheads I know and I'm one of them, do like to do economy driving. We have a simple system where we try to get into higher gears ASAP and keep the rpm below 3000 WITHOUT lugging the engine. I have a Honda City, which can be quite comfortable even below 2000. Infact, what we are doing is exactly what Jason says. Load it as fast as we can and keep rpm low, and NEVER ever brake (unless you relly need to, cause braking is waste of fuel). Try to coast near red lights and crossings. Blasting through highways and backroads is fun when you got loads of fuel, but can get real interesting when you are low and filling stations are far. Jason explained it engineeringly, ofcourse!! Thank you for another great video.
Hi Tracey, that CAN be a limitation.. But 3000rpm is still pretty good, and you are definitely gonna see gains.. Rather than cruising, most fuel is wasted during stop and starts like heavy traffic. A long time back "overdrive" gear used to be installed for this very same reason. Many people thought it was for going faster, but it was to keep rpms low at highway speeds. Engineering Explained will probably do a video on it pretty soon!! Safe driving Tracey :-)
What would be great to see is a comparison of mid term fuel consumption at the same distance between: 1) faster acceleration with higher rpm and immediately after reaching the desired speed, shifting into highest gear and keep it rollin (= short time of high consumption, long time of low consumption) 2) slow acceleration in higher gears to desired speed and keep it rollin (= longer time of mid fuel consumption, less time of low consumption)
Hey Guys Help mePLease I have altok10 1000cc petrol car from india ..I always used to keep 1000-1300 rpm So i thought i am theMOst intelligent person Onthis Whole universe 😅..My car is of 2013 cheap car . it dosent show fuel economy on odometre screen..So what economy i got so much years ? ..Car's 5th gear 2000 rpm is on 70km/hr speed ..why admin said 0.35 as early as possible and then said at 7.40 1500 to 3000..i Tested 2-3 times by tank to tank and it was 22Km/Litre with Ac. Company claims 25
In Austria you learn at driving school to keep the rpm as low as possible while driving, but speed up as fast as possible (to keep the acceleration time short).
From my own experience the longer you take to get up to speed the more fuel my cars use. Shifting early prolongs fuel consumption by not benefiting from torque multiplication and spending more time loaded. I coast a lot but take off pretty fast up to speed and I average between 3-4mpg better then rated on most the cars I drive using that method.
Granny who drives 10mph below the speed limit in the left lane had to chime in I see. "Noone should be passing me anyway im doing the speeeeed limit!" Try that on the Autobahn Gramps, get your electrolytes up... Sad...
Dubz0Eight You referring to Chris Sun's comment? Idk I don't think he meant it like that, I think he meant it is unfortunate to get tickets when you're just tryin' to have a fun time (smiles per gallon) in your car. But I would agree that "gramps" hogging up the left lane is quite annoying, I see people doing that ALL the time.
i just learned to listen to my car, i learned to drive in a manual, if you listen, the motor will tell you when the best time is to shift up, as well as shift down
The right time to shift depends entirely on how you want to drive it. You can always accelerate slower and rev lower on the way up, or drive faster and rev higher. Just make sure you match your revs to the tempo you want to drive at. If you keep it revved low while applying lots of throttle you're doing lots of harm, and if you keep it revved high while applying very little throttle, you're going to get more engine drag from the revs than you're delivering to the drive train and are just throwing gas in the toilet. Of course there's a sweet spot, and you need to adapt to conditions. The more drag forces are on you, the higher you should be revving before switching as well. If the road is torn up vs a clean pave for example. Going uphill vs downhill also, of course. If you always listen for the same sound all the time you aren't adapting to conditions and probably driving poorly a lot of the time
Most of the rolling resistance comes from the tread. Once the tread is worn down, you give the tires another 10 psi all around, and you're off to the races, so to speak.
Short version, keep it low rpm between 2k and 3k at whatever gear you're in. If you pass that it's time to shift. Now if you're a racer or you want to accelerate a lot, you usually go higher rpm before shifting for power delivery bc you need to get as much juice from each gear/rev as possible, but not go too high or you'll start forcing the engine and just waste power delivery.
@@Menon9767in benzin you shouldn't go above 3.5k even for power and for efficiency of motor durability and fuel efficiency don't go over 2.5k on any gear, 3k is also somewhat ok
It depends how much load you need. Is it more efficient to go round a car park at 3000 rpm in 1st instead of 2nd or 3rd? No you barely need 1000 rpm to go round a car park. 3000 rpm is enough to go on a motorway, so scale the rpm with the power you need. If you are really feathering the throttle and just rolling around urban streets you can shift up at 1500 rpm. If you need to climb a hill, 3000 rpm might not be enough. It's hard to measure load though as most cars don't have a torque meter, but as a general rule shift down if you are exceeding about 80% of available torque at rpm exceeding 2000 or 50% available if at 1500. Below 1500 only use a smaller % of available torque. Back off the accelerator or shift down if you are needing too much at low rpm.
Yeah, I remember reading that in 1981 in a "Das Auto" article about fuel economy. Old Idea that still works in most cases. EE said it right, as long as preignition does not occur.
Yup the short answer, shift as soon as possible. Other points would be: 1.dont accelerate while in high gear/low rpm, 3. Let go of the gas pedal while going downhill, 4. Dont use highways they ruin fuel economy...of course this advice is for granny drivers 😂😂😂
My older brother taught me how to drive manual transmission. He also taught me to shift by sound of the engine also... if it sounds like the engine is going to explode shift up, if sounds like its going to die, shift down low.
me too, mainly because my car don't even have a tacometer hue(in reality after driving the same car for a long time you kind of feel when you need to shift).
You mentioning BSFC few videos back changed my driving style and lowered my fuel consumption some 10% more (now reaching 50mpg with 2003 3-cyl 40kw 1.2 liter gasoline). Thank you for that. While you are at it, you should mention pulse and glide driving style that is closely connected with BSFC. You need to know and understand BSFC to understand PnG. I am really happy you care about fuel economy among other things.
@Jay Barker If your electrical appliances are consuming power and producing no apparent work, then most of it is converted to heat. Did you know that electric heaters are 100% efficient? Assuming I have 40kW capable engine and its thermal efficiency would be 40% (which is way too high for a gasoline btw), then I could say my engine CONSUMES 100kW in fuel it is using when producing full 40kW. BSFC values are in g/kWh and if I knew the kWh hidden in one gram of gasoline, then I could calculate the thermal efficiency map from BSFC map (I guess).
A kilowatt (output) is 1000 Newton force moved 1 metre in 1 second. If it required 200 Newtons (around 20kg on earth) force to push a car then 1 kilowatt would take it 5 m/s or about 11 mph. It is around 1 and a third horsepower. Obviously it will take more fuel burned because of wasted heat energy in an engine, which only converts about a quarter of the energy to force and movement (better or worse depending on load and RPM) Of course, there are different energy and power consumption that is measured in different ways. For example you could have kCal per second or BTU/second, which are defined by raising the temperature of water a kCal is raising a litre of water by 1 degree Celsius. A BTU is raising a pound weight of water by 1 degree Fahrenheit. You can in fact convert between mechanical and thermal and there are 4.1855 kilojoules (1000N 1m) in a kCal. With an audio amplifier, there will be thermal energy lost in transformers and microchips and then a set amount of electrical power delivered to the speaker. Of the electrical power delivered to the speaker, a lot will be lost in heat in the voice coil, a tiny bit lost in the cables and also some in the surround and spider of the speaker. The rest is transferred into mechanical energy in the air which is what you hear as sound, and even that becomes heat eventually when it has echoed round the room a bit and absorbed. The actual "wattage" in terms of force x distane over time of air compression is quite low (e.g. the amount of force compressing the air x the distance the air atoms moved/time to rearrange the air compared to silent still air), with even a single watt being as loud as a rock band at full bore, maybe taking as much as 100 watts from the speakers to do this. The coal burned to run the 100 watt amp might be as much as 400 watts back at the power plant, so your coal to music ratio isn't that good, although thankfully it doesn't take a lot of power to get LOUD.
It's true that thermal engines are only about 25% efficient. I've heard for the bugatti veyron, its 10 radiators are to chuck out the 3000 horsepower of heat along with the 987 horsepower of smiles when accelerating full bore. We can work this out. I've heard that a bugatti veyron at max empties 100 litres of fuel in 12 minutes. Petrol is 31.5 mJ per litre so 0.1389 litres a second is 4.375 million watts which is 5864 horsepower, so a bugatti veyron is only 987/5864 = 17% efficient?? Perhaps maximum rpm is inefficient though. There might also be some unburned fuel or partially burned fuel which is inevitable. An electric heater is 100% at converting electrical power to heat. Guess what, so is a light bulb. The light gets hot, and the light that shines is absorbed by you and the furniture and turns to heat. So are most other appliances. A television has parts that get hot and heat comes out the back. The picture of the TV is light that is absorbed by the room into tiny amounts of heat. The sound of the speaker(s) is absorbed also making small amounts of heat. A kilowatt TV (which would probably fill a whole wall it would be so big) would warm the room nicely whilst you watched, and awaited your electricity bill if you watched it a lot. So if you're feeling cold, and the house is a mess, you may as well vacuum the house to make heat. The exception is a battery charger which stores energy as chemical energy, until you use the energy in the battery for more heat! If the electricity comes from a coal powerplant it is not efficient though because you are turning heat into electricity and back, delivering less than a quarter of your energy back if you count conversion and wire losses. You may as well burn something like gas to make heat because the chimney losses are less than the power plant losses by far.
While i agree with you, there needs to be a caveat. Different engines have different power bands, Straying away from said power band too much, can ruin your mileage. I used to have a Mazda B2200 truck, 2.2 liter 5 speed, it liked to rev and averaged 25 MPG running in the 3,000-5,000 RPM power band, for acceleration. I sold that truck to my dad and he lugged it everywhere and only averaged like 18. asked me how i was hitting 25? I told him to treat it like a bike, rev it and let it run. He tossed me the keys and said, show me how you drove it. When i did, he was amazed it even got mileage, but he replicated my driving style and it instantly got 25 MPG all day every day till he got rid of it. You are right to a point, but the engine has a specific area it likes to and was designed for. if you stray too far outside that comfort zone it can hurt you both in mileage and also durability, because Spark knock is no joke, it'll ruin your engine bearings.
Every engine has different BSFC map, but usually similar to the one Jason has shown. The best way would be to measure your own exact map using probably OBD2 data (assuming the car has OBD2 connector). It is on my personal to-do list.
In "ecodriving" courses, it's taught that in constant speed, use the highest gear where the engine runs well (not lugging). This is consistent with your advice. Now, another interesting question is what to do when you're at a stop light at standstill, and you're going to accelerate up to let's say 70-100km/h. Then the advice is actually to accelerate fairly hard to get up to speed quickly, so that you then can use higher gear for longer distance. You didn't touch on this at much (actually the title of this video would better have been "what gear to choose when driving at constant speed"), but I think it's an important topic. Some people think it's fuel efficient to slowly accelerate, but this just keeps them longer in lower gears which is not efficient. So the advice for best fuel economy is to put in quite a lot of throttle (probably in the 1500-3000rpm band you were talking about) to get yourself up to desired speed, and then choose the highest gear suitable for that speed. Then another thing for fuel economy is to avoid using the brakes. So coasting is important, if you see well ahead that you're going to have to reduce speed, get off the throttle early, and coast in gear. On petrol engines, this cuts off the fuel supply completely, so as you're coasting, you're using no fuel. This means from highway speeds you can get approximately a kilometer of "no-fuel-used". I see way too often people maintaining speed almost up until the stop light or whatever, and then get on the brakes. en.wikipedia.org/wiki/Energy-efficient_driving has lots of these things.
Yeah, my thoughts exactly when I saw this video. I always accelerate quickly in a lower gear to get up to speed and then get into highest gear (usually 50 to 100 km/h in 3rd and then immediately 6th). It takes a few seconds and a bit of fuel, unlike other people that take forever to accelerate in higher gears and shift way too early (often even below 2500rpm, with a gasoline engine!). I hate being stuck behind such people because they ruin my fuel economy as well as theirs!! :D
Wouldnt that kind of driving increase the temperature too fast and put strain on the head gasket? Especially when you start driving in the morning after the car had been sitting in the cold during the night...
If the engine is cold then of course you should not rev it. What we're talking about is what to do after the engine has come up to something resembling normal operating temperature. We're also not talking about flooring the accelerator, we're talking about accelerating "firmly". In most cars this would involve using perhaps 50% of the available power (for normal cars, not sports cars), typically getting up to cruising speed in 13-15 seconds perhaps. So not flooring it, not revving to redline, just get up to speed in a comfortable short time. Some people will take "forever" to get up to cruising speed, and this is not fuel efficient.
Haha that would make so much sense as to why whenever i put resume cruise control on my grand marquis (lets say was 60mph now at 40) it freaking just steps on it.
whats good then it would be harder to understand. Sometimes it helps to pause and look/think about what was said. What made it most hard to understand (for me personally) was the pace he was speaking at. I had to pause a few times to catch up
I bought a Rav4 lately. 2004 y. 2.0 petrol 4wd. Friend told me that it's thirsty, around 12L/100km or so. Well. I've driven it about a week and my average is 7,6L/100km atm. Oh yeah I did throw one rear seat away.
I spend 80-90% of my daily driving in 5th. Although when people decide to go 10 mph under in town, I tend to be in 3rd or 4th. My 86 gets amazing gas mileage and it's a blast to drive.
Measurements at 58mph are an odd choice for determining "when to shift", a decision one makes when trying to get up to 58mph. I was hoping to see the differences between shifting at, say, 2500 vs 2000 vs 1500 rpm.
Shift at lower rpm without it straining/stalling the engine. I drive a diesel so almost impossible to stall I can actually (on a flat road) go through the entire trans to top gear at 30mph
That example was about fuel economy. The concept can be applied to determining when to shift if you’re concerned about fuel economy (shift as soon as possible without lugging engine). The test you would have liked to see would show the same thing, but would have been much more annoying for him to conduct.
It is written in the manual of my car, at what rpm should I shift to be fuel efficient. It actually translates into "as early as possible", as Jason said.
Finally someone to answer this question. I’ve been debating this with a friend of mine for over 20 years about this. He insists that keeping the rpm as low as possible is better efficiency I always said shifting at the peak torque point is better regardless where that is in the rpm will be more efficient. Looks like i owns him a Coke
Peak torque doesn't necessarily correlate with the best BSFC, but it often is the spot with the greatest volumetric efficiency. That's intuitive, since the region where you make the most torque would likely be where you pull in the most air, relative to the size of the engine cylinders.
Kristopher Klassen I don't agree with higher gear statement. I offten get higher fuel consumption on higher gear and not accelerating, just steady right foot. It may be car specific and also different elevations lead to different results.
i used to shift at 2500 on my NA 1.6l inline-4 and it felt very sluggish and returned about 11L/KM, now im doing 10.2L/KM shifting at 3000 except on a descending stretch, where i shift at around 2200.
Kristopher Klassen. Engine should be rev happy by apllying no more as 30% of throttle, And there comes to play in how RPM you should change gears. Engines, Cars, And gearboxes Are diferent. Nothing absolutely Universal doesnt exist. But that 30% throttle rule simply rules 😁
Experience from 40 years of driving taxi driving in Sydney, Australia. Mostly in approximately 4:0 litre, 6 cylinder, automatics. Lights change to green, give it a bit of a boot - again, a bit of a boot - then back off. The gearbox will find the highest, practical gear, by it's self. When I drove my own, Falcon GT manual, in suburban areas, I used to skip-shift a lot.
Engineer here. - when going at a constant speed, use the highest gear you can for the lowest RPM - when accelerating, use the RPM ranges that has a higher torque/RPM ratio. Look at the RPM/torque graphs of your engine (the dyno tests give you these), and select the last RPM point, where the graph is at a 45 degree increase. That will be the recommended maximum RPM.
I'm always amazed by how smooth your presentation is while you're driving... If I'm driving around curves, I usually stop talking or repeat myself or go "uhhh" a lot
@@JarmalK just that a real spinny boi makes for a heckin lot of heat n rubbing. Which may shave down your cylinder wall and let the floaties hang aboot. which to your engine feels like running on a beach with sand in yer crack. Its hott components also grow thrice its size, like the grinches heart. And then stuff dont really line up as awell. But EE is a gangster and doesnt play by the rules. Gets results.
Your test is kind of incomplete because you tested the coasting efficiency of each gear but didn't test the differences of efficiency to reach that speed under acceleration. If the goal is to reach a certain speed, it may be more efficient to do it quickly with less duration of load rather than slowly while being under throttle for a longer amount of time. I'd really like to know where the balance is.
To get your car down the road the most efficiently you want to produce the power needed at the highest efficiency. It doesn't matter whether that power was used to accelerate or maintain speed. Jason makes it clear that the highest efficiency for most engines is between 1500 and 3k rpm and full load, meaning at cruising (low rpm low load) or at brisk acceleration (high rpm, high load), your efficiency is worse. Why would you want to take a long period of high efficiency and replace it with a shorter period of slightly worse efficiency followed by a period of even worse efficiency? A second good point is that accelerating faster, you have a greater tendency to 1) overshoot your desired speed, which is not advantageous for economy or 2) have to brake harder if, say, the next light turns red.
@@tscook10 you're looking at this from more of a broad physics perspective than a car physics perspective. Saying most engines are efficient between an arbitrary rev range (pretty wide one in the eg) is too much of a blanket statement. You could have two of the same exact engine running different fuel maps and ignition timing and that claim could easily be made untrue. And the coasting efficiency would end up the same after the target speed was reached, as the car would be shifted into overdrive, so it's irrelevant.
@@Shakshuka69 , I agree, when speaking in generalities we can't be specific but I think it is important to note that the vast majority of production cars, in stock form will be most efficient at some specific speed between 1500 and 3k rpm and that above that speed they get less efficient. The exact shifting point for peak efficiency will vary by car to some degree. However, We've already established that accelerating at peak load will br more efficient than part load and if you're asking whether it will be more efficient to shift at 3k rpm or 6k rpm I would say, with very few exceptions in the automotive world, that the former will be most efficient.
This is something I was hoping he would have touched on. While everyone is stating the engine is most efficient in low rpm high load, the vehicle is most efficient in the highest gear. So although the engine may be most efficient in any given instant running through the gears as quickly as possible it would probably be more efficient to accelerate quickly and get to the highest gear as quickly as possible. A perfect example of when this technique is likely more efficient would be something like a high way on ramp. I’m glad you brought this up and wish engineering explained had covered the concept of rush to idle because as it sits this video only discusses where the engine is most efficient and not when the vehicle is most efficient. Ironic consider he briefly acknowledges that he’s not really discussing fuel economy at the end of the video.
Shifting as early as possible during acceleration will put you in the highest gear possible at any given time. Combine this with the fact that, typically, engines are most efficient at low rpm, then it follows that the most efficient way to accelerate is to shift as early as possible without lugging or possibly a bit later if the efficiency peak is particularly high in the RPM range.
cl4ster17 Depending on the generation of diesel you're running, that might not be optimal as you may be increasing your maintenance bill in the long run. Older diesels tend to get the turbo and the air paths clogged with sooth if you are mostly out of turbo boost. Also, if you're always at low rpm, high load, your flywheel may suffer as the vibration is increased. Older diesels, such as the VW's 1.9TDI run best when shifting at ~2500 rpm. Yes, your MPG may decrease, but the amount really is insignificant. However, newer diesels are designed to run as much as possible at low RPM to reduce fuel consumption.
I don't always agree with Jason (see Mercedes Clever Turbo Engine), but as a mechanical engineer specializing in internal combustion engines, I think this video hits the nail on the head. Don't over rev the engine, but as you accelerate shift into higher gears at lower RPMs. I own a Cadillac ATS 2.0T with a six-speed manual transmission. It's rated at 20 MPG city and 28 MPG highway. Over the last 45k miles, I have averaged over 31 MPG overall in mixed driving -- more in the summer and less in the winter. (Yes, I record everything.) It's not difficult to do. Jason's comparison at about the 3:40 mark in the video is excellent. And, yes, BSFC and MPG are different concepts. Now, let's do this same video using a car equipped with a Diesel engine. (Note Diesel is capitalized because it's a person's name.) Good video.
In my 6mt forester I noticed I can shift into 2 at 20mph, 3rd at 30 mph, 4th at 40 mph, 5th at 50 mph and 6th st 60 mph. I discovered this after plugging all my gear ratios into a spread sheet. I wanted each shift to drop the rpm to around 2000 rpm. I then noticed that each shift brought the mph to near what the gear number is.
Yathu prem He's a videographer trying to tell a story. Not everything has to be sequential or in real time. I'm not offended by that but it amazes me how many are.
Modern cars have shift recommendation displays that you can use as a guide. Economical means accelerating quickly to the desired speed, shifting up as early as possible and driving with foresight. The most economical speed on the motorway is between 80 and 100 km/h (50-62 mph). Speeds over 140 km/h (over 86 mph) should be avoided because the cars consume above average fuel due to air resistance.
I drive 60 miles a day on highway and here is what I found. 1) be in max gear. 2) drive close behind semi trucks or any slow and large vehicle. driving at 54 mph (90kmh) is usually where cars have the highest MPG. BUT air resistance is taking the numbers down, thats where following trucks is important, they create a depressurisation behind them, see them as boats and try to stay in their wake. now, keep a safe distance, but keep in mind that trucks dont brake as hard as you can
You kinda ignore something important here. Throttle setting during acceleration. You're actually using up most of your fuel accelerating, and here's where I see most people screw up. For some reason people think gentle acceleration makes for high fuel economy. Starving the engine of fuel never allowing it to get to peak efficiency...
Imrahil its funny, i have a first gen miata and have done back to back fuel economy test. accelerating hard and blasting around town gets almost exactly the same fuel consumption as accelerating as slow as possible. im not saying your wrong tho. It shows that cars dont like accelerating slow. doesnt help consumption at all.
I own a second generation Miata and experience the same thing. Shifting early (below 25kRPM) yields less miles per gallon than at 3-3,5K RPM in practice. And is less fun ;). It seems they reward a quick (but not mental) driving style.
@Engineering Explained Our Mini Cooper S 2014 has fuel economy digital gauges built into the dash when the driving mode is set to 'eco'. What I noticed is that these gauges seem to show worse fuel economy the more load is on the engine, irrespective of engine RPM. Are these gauges incorrect? The video suggests lower-medium engine load is required to achieve good fuel economy, as long as revs aren't too high. But I'm pretty sure that loading the engine at say 30-50% at 2000rpm gives a worse result on the gauges compared to say 20% load ('load' meaning throttle position more or less as I have no other way of measuring it). Sorry if this question sounds complicated but I'm curious. I have not tested this using the real time fuel economy figures of the trip computer. I wonder if those would tell a different tale to the 'eco meter' gauges I'm referring to.
+9000Redline That's probably because it's using a small amount more fuel per metre at higher load to produce a significantly higher amount of power at the crank. Practically this means that you'll be accelerating during this high load scenario until your speed increases and your losses to aerodynamics outweigh any efficiency gains, but it also means you can get up to your desired speed quicker where you can reduce the throttle, using less fuel overall. Try this (if you're in a car with a manual box and have a long empty road): If you usually do 100km/h, accelerate at high load (~70% throttle) until you get to 110km/h, and then shift into neutral. At idle, in neutral, the engine and gearbox friction is minimal, and so you're using very little fuel. Once the car reaches 90km/h, put it back into gear, and again accelerate until 110km/h, putting it back into neutral. While doing this, If you've got a passenger, get them to periodically take fuel economy readings (once every 5 seconds or so, even when in neutral and coasting). See if these values average out to more or less than a reading taken at a constant 100km/h.
And switching from 1st gear to 3rd gear, skipping 2nd is another way to be efficient. I usually don't even use 2nd I build rpm on 1st quickly, jump to 3rd build enough to get me through 4 "faster", and I then switch to 5th and remain there till I build just sufficient rpm to get to 6th for cruise.
Hey Guys Help mePLease I have altok10 1000cc petrol car from india ..I always used to keep 1000-1300 rpm So i thought i am theMOst intelligent person Onthis Whole universe 😅..My car is of 2013 cheap car . it dosent show fuel economy on odometre screen..So what economy i got so much years ? ..Car's 5th gear 2000 rpm is on 70km/hr speed ..why admin said 0.35 as early as possible and then said at 7.40 1500 to 3000..i Tested 2-3 times by tank to tank and it was 22Km/Litre with Ac. Company claims 25
When I was learning the mandatory echo driving I was instructed to accelerate as quickly as possible in low gears and skip a gear when I get to cruising speed. For example, if you are approaching an intersection you slow down as usual. Then when you are in second gear complete your turn, you quickly accelerate up to speed and go straight to 4th gear. I was told it uses up to 80% less fuel than accelerating at a normal speed and not skipping gears. I don't know if it's true or not, but it is in my muscle memory now and I still do it.
if you skip to the 4th gear you dont use the 3rd, which is kinda bad cause u don't wear it out making it uneven with the gears. (hard to explain, english is not my native language sorry)
I drove my 1999 Honda CRV manual for over 8 years. Over time, I figured out that 2500 RPMs was the sweetspot for MPG. when I drove it, I keeped it around 2000 RPMs when going downhill and 2500 RPMs when driving Flat. It also made the car great for sharp back roads because it also has a short transmission because 2500 RPMs in fith gear is 50 MPH (which is also when it got its best fuel econmy of 28 MPG). Also, I learned if you want to get up to speed quickly for some reason, like going up a hill to merge on a highway, then you shift at 4000 RPMs. Any higher than that then your going to start buring a lot of fuel, any lower than that then you will be in fifth gear to quickly and not have enough power to get up the hill!
I was going to ask "what if you don't care about fuel economy but only want to accelerate as fast as possible?", but then you addressed that very topic in the second half of the video AND mentioned that there's a separate video dedicated entirely to that. Great video and channel!
A few other things to consider: Gasoline engines run most efficiently at the RPM of maximum torque which is around 3,000 RPMs for most 4 cylinders, give or take around 500 RPMs. Accelerating at wide open throttle up to around 3000 RPMs before changing gears I've found gets me the best gas mileage. Although I rarely accelerate at wide open throttle in first, it's a bit too dramatic in a rather fast car. :). At wide open throttle not only do you have a lot less vacuum in the intake resisting the engine but the intake air rushes more violently into the engine giving better mixing of the air and fuel, giving a better combustion efficiency. This increase in combustion efficiency is part of the reason torque goes up so noticeably around 3,000 RPM. The other reason is the air velocity in your intake runner hits just the right point to do a little supercharging of the cylinder. My driving style is to stay at wide open throttle as much as possible but not going over 3,500 RPMs too often. I like to accelerate up hills WOT in 5th and then coast down hills. My car is rated around 35 city/40 hwy, but I average 47 in the summer, 44 in winter. I'm not a slow driver either and I get up to speed quickly even though I shift early because I have a rather fast car with a light weight flywheel, 135 hp honda crx(2000 lb). I coast to stops a lot as well.
@Richwell Robles I tried this driving style in a 2007 Honda Civic with an automatic transmission. I can't go wide open throttle or the RPMs go too high. I can barely push on the throttle at all which really sucks. However it does coast very well when taking your foot off the gas and I can still use that technique. It would be a lot more efficient if you had to go to about three quarters throttle before it would downshift. I average between 35 and 38 miles per gallon in that car. I think it's supposed to be 32 in the city and 36 on the highway.
"shift up as early as possible": off course. But my question is always: how to safely determine what is "too low". I really like to roll near idle speed. How to determine when a (bigger) engine is suffering from low RPM? (below idle it's gonna starting to jump, that's clear.)
You will know; it starts jack rabbiting or you can clearly hear it ping. So what you do is teach yourself how you engine works by gradually trying how much throttle you can apply at increasingly lower rpm. In my my car I can safely do 3/4 throttle from 1100 RPM in 5'th gear, that is when I'm only going 25 MPH. That way my accelerations are fuel efficient from that speed and accelerating further to 30 or 45 from 25 in 5'th, gives me a mileage of 40 MPG. If i did this in 3'rd and 4'th I would be in the 25-30 MPG range while accelerating.
For my engine, the manufacturer says to always be above 1500 RPM. However, being an inline 6, the engine is very smooth from idle to rev-limiter, so I often find myself accelerating in 3rd gear at 1000 RPM. Of course, I do not go full throttle from those RPMs. If I need to go full throttle, then it means I need a lot of power, which, in turn means, I'm definitely in the wrong gear :)
Manufacturers don't recommend it but that is because they don't want you to lug the engine, which is to hard on bearings and piston rings, but you are not doing that, you are easy on the pedal at first. A test you can do on a piece of flat secluded road is to lift the foot from the accelerator at slow speed 25-30 in highest gear and note of which speed is settles down to ( you basically drive at idle RPM). Then carefully apply throttle in a way that increases your speed but does not strain the engine or make it bounce and you will notice as the speed slowly creeps up together with the RPM, you can safely apply progressively more throttle, and 1600 RPM sounds about right as the speed where the engine regains it normal responsiveness and you can apply more than half throttle without problem. In my car I can apply full throttle from 1500 if I wish. You basically want to feel as sluggish as if you car was overloaded full of garden tiles. Careful on the throttle and be in top gear from 20-25 or what is possible with your car until you hit 30 and can accelerate normally. That way you'll use the least fuel to get going as the car needs to fire the fewest number of cylinders to get you up to speed. You can't do it if traffic is too intense, other drivers will go nuts on you. You probably already do it occasionally when starting in second by mistake and don't bother to shift down, just being extra careful on the pedal until you get up to normal second gear speed.
Yep, I do all that :) If I'm going at constant speed, I'm usually in 5th at ~40 mph. My car has rather short gearing, so, at that speed, I'm turning 1600 RPM, but as I mentioned earlier, I don't necessarily follow manufacturer's indications. I just make sure to load the engine in accordance with the RPM.
Everyone keeps recommending a certain RPM when shifting but here's my best advice: All cars are different - gear ratios and engine torque; Simply find that point where your car doesn't jerk in between quick upshifts while taking note of both the RPMs and the upshift speeds you are driving at. When you engage the clutch a bit quicker than normal.. you can tell when you've found that point where the RPMs/engine speed matches the drivetrain speed as there is little to none RPM drop once the clutch has fully engaged on the higher gear and you can definitely feel the silky smooth shifting (2 finger shifting) without waiting for the synchros to slot the gear lever in from a lower to a higher gear. (faster clutch in and slower clutch out but a little bit quicker) For downshifting, just memorize the speed where you upshifted for all the gears so you can downshift a bit faster (less clutch hanging or none at all) you can save your clutch with minimal wear and you don't have to rev match the engine if you're not on a spirited drive. Save additional gas and clutch usage by always giving distance to the person in front of you to minimize clutch balancing in stop and go traffic. I have found that this works best for me regardless if I'm driving a turbo V8 or a twin turbo inline 6. I'm getting 21-27 mpg in the city which isn't bad in my opinion. Hope this helps y'all (:
modern small turbo engines thanks to higher torque at low rpm allow early shifts, which translates in amazing efficiency if you know how to drive. I can run under 1500 rpm all the time if i really want.
is it 90 hp? it can't do miracles, I have twice the power and probably only a few kg more, so obviously your engine has to work harder to move the car.
I've driven all types of vehicle with anywhere between 3 and 16 forward gears, and when I started learning, I was told to change up as early as possible, and that served me well, because it easy to tell from the behaviour of the engine if you change up too soon. I have driven automatic cars, and 40 ton dumper with an Allison 5-speed, but I much prefer manual gears. I particularly enjoyed changing gear with a crash box and judging the right revs to slide into gear without any painful grinding noises.
I normally stop upshifting when I get to either fourth gear or sixth gear, sometimes fifth. Sixth gear is the highest gear I have for cruising at high speed on the highway and fourth gear is more practical for cruising at lower speeds between signal lights in town. In other words, fourth gear is my city driving gear and sixth gear is my highway driving gear.
Actually most HGV drivers have three gear ranges in one gearbox, which theoretically gives them 18 gears (6 individual gears, 3 gear ratios) - but most truck drivers will jump many of them, dependent on how heavily loaded they are and what kind of incline/decline they are driving along, as many of the gears in the whole set are so similar that there's no point using them all.
Best fuel economy? The slowest you can go, in the highest gear you can go without killing the engine. 1000-2000rpm and 50kph is a really efficient spot. Even if you're not in top gear, air resistance really kills your mpg, so its often better to switch to a lower gear and slow down.
Great video as always! Can you make a video explaining exactly what load is and how it is measured? I think I understand the idea, but I'd love to learn the details and physics behind it.
best explanation for those who dont know car like me is > when the car is growling or right before it growls you change to higher gear, when the car feels like its having a problem or like its gonna stall or if its vibrating you go to lower gear.
I have a question that is perfect for Engineering Explained: Is it more economical to to a reasonably fast acceleration to the desired cruise speed or is it better to do it slower? The variables are interesting - the time spent accelerating being the one that springs to mind first. Hope you can make a video on this, if you haven't already. Great channel, by the way - I learn so many interesting things! :-)
I experimented with this quite a bit on long daily commutes on roads with lots of traffic lights, about 15 years ago. In my petrol BMW 318i at the time, I found that quick acceleration (not flooring it, of course) to the desired speed, was more fuel efficient than long, slow acceleration at low RPM’s. All acceleration uses a lot of fuel. Doing it for a shorter time and distance is obviously better, provided that it isn’t offset by the difference in fuel consumption. I could not replicate the results with the cars I’ve had since, all diesel BMW’s.
This is my suspicion too, but it would be cool to see some data on where the line goes between too slow acceleration and too fast acceleration. It may of course depend wildly on the car. I drive a Citroën 2cv in the summers, and it has a 29 hp 2-cyl 602cc engine, and full acceleration in that is basically a normal acceleration in a normal car (or even less). Spending 2 minutes getting to cruise is not useful, and I'm going to end up at high RPMs anyway. Maybe the goal RPM range is indicative of some of the variables here. Food for an engineer's mind, or what?
Jason basically explains it in the video, but you have to go one step further with the explanation. You want the engine to be at high load in the area of peak efficiency. For a lot of cars that's between about 1600rpm and 3000rpm. It doesn't really matter how long it takes to accelerate since the point of acceleration is to turn chemical energy in the fuel into kinetic energy in the car's mass. The only thing that tells you how efficiently that is done is: Break specific fuel consumption. It takes the same amount of energy to accelerate your car from x-mph to y-mph whether it takes a 10 seconds or 20 seconds (Let me put in right here that there is a heavy qualifier here that you are accelerating at some moderate pace at legal speeds where the amount of power accelerating the car is much greater than the amount of drag on the car, i.e. the amount needed to maintain speed, luckily, full load acceleration at 2k rpm and 5k rpm are likely within this range). Basically, the longer you can spend at the highest efficiency level, the better. Your cruising bsfc will almost definitely be worse than your accelerating bsfc, so why would you want to get to that earlier?
I play by ear and can even feel when it's ready to shift to the next gear. I barely or look at my gauges when to shift but that came with practice. You can even float to your gears without clutching which can save some wear on your clutch as long as know what your doing but wouldn't suggest it to beginners. Just practice and it'll become second nature.
I was just looking for a video like this! Time to save on fuel when on the daily commute & floor it in the weekends to make up for all my savings haha Right on time :)
Agree, i drive a 2014 civic si, the rated is 31, i got 37mpg once for about a month, but i usually hover around 35mpg...i change gear at 2500rpm, this gives me enough power to pass 80% cars on the road
@Jay Leno I agree, but most of the small cars at 40mpg or 45mpg during that time were around 130hp would have been no fun to drive. The si with 205hp allows me enough power to switch lane quickly, plus the reliability of a daily, cant say no!
wow.. Real science and not just opinion. My modern VW's manual say very similar for fuel economy. The manual taught me a lesson though I was sceptical. I was taught to get into top gear as quickly as possible so usually revved high in low gears ... did that for years. with my new VW i was getting good economy with the old style of driving but after reading the manual i decided to give this new style a go. fact: noticeably better by approx 7mpg in urban use! worth doing in my experience.
I really don't think this video answered the question. It still needs to address whether to to shift early during acceleration to reduce fuel consumption or do it later to make the time driving slow and inefficient a bit shorter. Also how much throttle should the car be given. This is not truly explained, but only touched upon. I would like to hear an explanation about finding a sweet spot for how fast to accelerate alongside when to change gear.
In a turbo engine I get a bit better gas mileage if I stay in a lower gear and not use turbo boost (air fuel mixture gets way richer once you start to lug the engine at all). So if I go up a hill in 6th I get worse gas then if I stayed at higher rpm in 4th or 5th and just stay light with the throttle
James Banks I wondered about this since I have a 2016 WRX 6-speed. I kinda want to do some testing to see what kind of efficiency it is capable of. But the darn thing is just too much fun to drive fast!
honestly this guys super in depth and all but he gives u the best advice right away. Shift as early as possible. I hate to say it but its really that simple the rest of the video is just overthinking
I remember having an up-shift timing indicator light on my 1992 Ford Tempo. It seemed based on the manifold absolute pressure that depended on the load of the engine and throttle position. Also, the 1980’s BMW’s had a needle with a L/100 Km gradation probably linked to MAF.
Assuming your CVT actually works as a CVT and isn't programmed to use predefined gear ratios just to feel more "normal". Really want the best economy? Get a BEV.
Of course this is the basis of the old "Shell Economy Run" burn and coast technique. It's amazing what can be accomplished by this. When forced to make a 350 mile trip during the 2000 fuel shortage in the UK I got just short of 50 MPG (that's an imperial gallon!) out of an E34 BMW 525i by burn and coast (and tyre pressures on the high end of the permitted range). It felt like I was peddling the thing the whole way with all the into top, boot it, into neutral work required. Going back far enough some UK cars were fitted with free-wheels in top gear to allow this to be done without all the legwork.
Thanks this was really helpful! But i have a question: Does this apply to acceleration aswell? You mentioned staying 60 MPH all the time which is quite self explaining, higher gear = lower fuel consumption, but what about accelerating to a specific speed and then shifting and holding the higher speed in the highest gear? Can you do some Tests about that too?
I cant believe this needed a video... its no shock lower RPM is going to give best mileage... NOTHING is more satisfying than being a manual shift driver, experiencing your first CVT. Its incredible technology. You can get up to speed on the highway NEVER going over 2k RPM's exploiting the full distance of the on ramp. And it just chills there at 70mph at 1.5 RPM. ITS AMAZING! In my V6, 6 speed auto Lexus Its 2.5 RPM at 70MPH, in my Altima its 1.5RPM at cruising. Im just amazed.
Always impressed by your deep knowledge, you turn something upside down that I was led to believe by a trusted source long time ago. Their wisdom was, accelerate as quickly as possible to your desired speed and when there go to the lowest gear still safe/comfortable. The idea was that acceleration in the lower torque and power region of an engine would cost relatively much total fuel, even when consumption during a brief brisk acceleration is very high. So you say this is not true? And I have been living with a lie all those years? I think I'll keep the old version to justify down-shifting with rev matching to a gear that gives me the beginning of turbo power, and floor it. And between 60 and 70 m/h put the car on cruise control in 6, with over 60 mi/ga economy. :)
My ‘84 Peugeot 505 GL manual said that for the best fuel economy, shift into a high gear as soon as possible. That doesn’t mean to floor it, but not to dilly-dally in lower gears.
we want the same expiriment you did with a diesel engine this time!! to see how much of the benefit comes from pumping losses and how much from added friction!
Engineering Explained Would it be an old TDI VW. I don't know of any diesel cars on the road. Because America only has very few diesel cars. I think Chevy has a little diesel in their new Equinox.
Yes, but the test shows different conditions. The car goes up and down hills, where it has to accelerate to maintain the vehicle speed. We're demonstrating that BSFC is best at high load, low RPM, so if you want to maximize your efficiency while accelerating, you'll be better off with a higher gear at a higher load, than a lower gear at a lower load.
It was interesting to see 4th and 5th gear comparison while going up and down hill. 4th being slightly more efficient at some points. It would also be interesting to do this same format in combination with your coasting video. Maybe also an acceleration run with a block under the accelerator to hold it at a certain point while changing gear at different rpms?
Ok so this a great video. Although I must say, this is highway driving. To keep it simple as possible, if driving in a busy city drive as though you don’t have a brake (engine braking) and simply use the actual brake only when you really have to. Just by doing that your fuel economy changes to the better drastically.
I had a 1987 gutless Toyota 22R, 4 cylinder pick up, about 100 ponies. Didn't matter when I shifted it never had good torque and never had good power, seriously, useless in passing.
Correct me if I'm wrong, but don't you take the best of every fuel drop when the engine is working at it's higher torque zone? I mean, if you are in an uphill, won't you be taking better advantage of the fuel used with the engine working at it's optimum torque zone than with it working at low rpms meaning that it is not working at it's optimum point? Thanks!
The video shows where you get the most power per amount of fuel, which is the brake specific fuel consumption map shown. This doesn't necessarily correlate with peak torque.
Engineering Explained Is there any resources available to show the bsfc for a given engine or are there any correlations you can make from the more common dynograph?
the fuel entering the engine is burned almost 100% almost all the time. So per gram of fuel entering the engine the same amount of energy is being prodused. from that energy we end up using about 25% and the rest is being lost. But when you operate your engine at low rpm you have less friction forces to evercome and less pumping losses becouse you have to open the throttle more to create enought power thus letting the air pass easier. so we end up useing 29% of the burned fuel for example. to conclude its not that we take better advantage of the fuel but redusing the energy losses.
If you want power higher go higher rpms, if you want fuel economy go lower rpms. This is pretty basic knowledge which we already know but glad someone is making money reiterating it.
Hi Jason, I've been trying all types of driving and shifting methods over the last 10 years with my 2009 Tacoma 4.0 litre and logging it. Not scientific, but over time I can see trends as well as tank specific mpg. After using this method, my last four city-only tanks of fuel have yielded 22.2 - 24.7 IMP mpg (Canadian here). Previously, I was getting 17 - 19.5 city-only IMP mpg. I previously was driving in 3rd-4th gear at 60kpm, shifting at 3000rpm and coasting at 2200 rpm and using a vacuum gauge to try and get the best mileage (as I was told that the highest vacuum numbers = best mpg). NOW, I'm shifting at 2000rpm and ending up in 5th at 60 kph with my rpm's at 1450. I'm assuming that "lugging the engine" would be any chattering or vibrating during acceleration in too high a gear? If I need to accelerate, I'll drop into 4th or 3rd. The vacuum gauge still gives high numbers, but drops more easily and quickly, with less pedal input in a higher gear as opposed to in a lower gear. Anyways, thanks for all the great content! I was posting more to confirm and illustrate to others the effectiveness of this method, rather than tell you something you already know and made a youtube video of... :) Ps, I'm lifted 3 inches and running 33's, so I'm really happy with the results, especially!!!
Here are two additional videos which supplement this nicely, hope everyone's having a great day!
When To Shift For The Best Acceleration - ua-cam.com/video/zZBqb0ZJSwU/v-deo.html
LSPI: Don't Lug Your Engine - ua-cam.com/video/soJea7xEt-8/v-deo.html
Does this also apply to diesels, since there are presumably no pumping losses across the throttle plate to worry about, and where one needs to get the turbo spinning to get efficiency?
Engineering Explained - Thanks for the next link. I am a 31 year old Mom that just got her license last year - had a huge fear of driving - and now I've been doing research because when I started driving I had a Jetta and I taught myself to drive in her. My next car, a Monti Carlo (did I spell that right lol) wasn't a manual and I hated it. She has problems with the transmission wasn't changing gears fast enough imo, and then she overheated and it went down hill from there. She's currently in the shop. My Jetta long gone by this point. So my Wife surprised me with a manual 95 Jeep YJ, she needs work done to her. Cosmentic and a few things under her Hood but for the most part she's perfect imo. Point of this comment is I've been watching a lot of your videos so I can tinker myself on the Jeep. And even though I taught myself to drive the Jetta, I don't know all the right ways, seeing as I know just because I can get it moving doesn't mean I'm doing everything right in the long run. Lol. So thanks for these types of videos! I need to get better at changing gears at the right time. With this video I now believe I have been changing gears just a bit too late in the Jeep. She's older than the Jetta was and I have to get used to how she ticks. Thanks for the help! :-)
The thing is, the bsfc maps are created at "steady state" conditions, which is close to what you show in the constant speed test. But acceleration is a "transient" condition, so how can you know where you are on the map?
Some years ago, I recall BMW saying that for the best volumetric efficiency, they recommended flooring the throttle in every gear - and shifting at 1500rpm. This is probably a little extreme, but the principle is the same.
I've used this technique on long road trips in an '01 Focus ZX3 (so I generally shifted at 2000 rpm to avoid lugging - it was not exactly a torque monster.) I achieved an average of 35 mpg, at an average speed (including stopping for fuel) of 65mph. All by using the maximum throttle opening I could use for the speed I wanted to do, and sticking to the highest gear I could get away with.
My manual says something about NOT shifting to early. After 2 weeks trying to get better economy I ruined my cap, and rotor.
The best time to shift gears is when your right foot is touching the firewall and the rpm needle is sword fighting in the hotzone
Stewart Mckinna well I was going to say something witty but you beat me to it
Stewart Mckinna Hahahahaha,the best comment that I saw in this week
And depending on what you consider best, sometimes true! ua-cam.com/video/zZBqb0ZJSwU/v-deo.html
Fuel economy is lame. Gas is cheap. If you want to spend less on gas, get cheap beater cars.
@@TheTurpin1234 depends where you live. In the UK regular unleaded is around $6.30 per US Gallon. I wouldn't call that cheap
Shift to R for "Really Efficient" mode
It can also be a Race mode, depending on the gear you were in before you select it. :)
(Please don't do that.)
Its going backwards
O!Technology no no no.. that’s rocket mode my friend
You got it ! ............
Didn't work. My car made a loud click and jerked, then it just went into neutral. Put it back into 6th. Good thing it was a rental.
EE: Fuel Economy
RX-8: We dont do that here
Unless it has an LS
😂🤣🤣 lmao
Brandon Sanchez don’t ls’ chug gas too? It’s a v8? Idk much about mpg or what good mpg is just asking
@@melissahollandsbiggestfan5812 even the 3UR-FE is a gas guzzler.
The rotary actually gets better mileage at (somewhat) higher RPM and lower load (throttle opening). At 35 mph uphill, if I use 6th gear it takes a lot of throttle (around 1500 rpm) to maintain speed and the mpg goes down to 6-9. In 4th gear, it's loafing along at 2500 rpm or so, and the mpg is at least double that. For a light car (weighs the same as a Civic), there's a really big mpg difference between uphill and level.
The rule for a rotary seems to be the opposite of a piston: use whatever gear you need the least throttle to get the amount of power you want. Generally 2500 - 3200 rpm seems to give the best mileage. Above 3250, the SSV valve activates (it switches to the high-rev intake tuning) and above 4000, the 5th and 6th fuel injectors operate.
FYI: at 60 mpg on level ground without wind in 6th, I get around 28-32 mpg. I did an experiment, and drove it like a Honda for a week, about half city and half highway, and got 23.4 mpg for the week. Driving a little "enthusiastically" and completely city driving (lots of sitting in traffic) brings it down to 18-19 mpg.
It's a completely different beast.
Keep revs between 1500-2000 while cruising, accelerating dont let them get above 3000.... pretty basic really
Tamlin Giles my 6th gear is at 3000 rpm at 60mph lol, that’s the highest speed limit in my country.
Jack Vinall mine gets up there too when I’m on the highway but you cover more distance without stop lights and constant shifting through gears. So it works out to be just as efficient
I have a Mazda 6 and it usually at 3300rpms and 50mph in 5th gear. I wondered how it keep its efficiency
depends on the car, my truck cruises at 1000 rpm and shifts at 1600 rpm
I always start from 2nd gear
I only first gear if im on an incline
As far as shifting , I just keep my rpms as low as 1500 to 2krpms since my car has enough torque to get it moving
If you're driving a car with weak torque, then you need higher rpm (a honda civic for example) vs a car with high torque (a camaro for example)
I followed the thumbnail and shifted when the fuel tank was empty.
How many mpg did you get?
@@thearousedeunuch Eleventy.
@@dchawk81 😂
This is gold.
اما كذا يابو علي😂😂😂
Yes, this is a highly detailed, well presented (a little long winded) explanation.
Here's the short version; shift at as low an rpm as you can without lugging the engine. Once you've done this a few times it will become second nature to you.
Yup common sense. Don't accelerate harshly, and keep it in fairly low rpms and not high speed, but not too low rpms so as to do damage.
Exactly. I'm always Driving between 1.5k - 2k RPMs with my 306 GTi, but without lugging the engine. It doesn't matter how higher revs are efficient, 2k RPM is always half of 4k RPM, so it will burn fuel slowly.
@@mryan4452 However, not accelerating hashly does not mean that you shouldn't go full throttle. Some people might think that much throttle means much fuel.
In a diesel car such as mine with 3.0L
This is me.
Everytime I change gear the only RPM where it can still move without having a vibration is more than 1.5k lower than that.
It'll start to vibrate itself which isn't that great.
The lower the gear the higher RPM is the time when you change your gear.
As for me
1st would be around 2.2
Same goes to 2nd and 3rd
4th would be 1.8RPM
All of this are the RPM when I change my gear.
It'll go back to 1.5RPM which is the best spot for me.
Different cars may have different RPM when to change gear.
After using your car a lot of time you'll eventually know when you'll change your gear in the most efficient way possible
Can you please describe what "lugging the engine" means in this case?
really liked the 4 split screen with added graphics
Happy to hear it! When I put it all together and watched them side by side the first time I was so excited haha.
Very good explanation, great shifting is acquired by feel. Feel of the vehicle with feel of the road. Generally the heavier vehicles will require higher RMP's. The automatic transmission was invented for women drivers that demonstrated the lack of feel for such machines...
Engineering Explained thanks Jason for confirming my suspicions of a newer manual 7 or 6 speed is way more gas conservative ( @ 60mph~ ) vs a 3 speed non locking 60s automatic transmission
I found that one by accident using a turbocharger calculator and reading about other peoples builds getting better mpgs
I’m only part of the way through my build changes so I’m not to where I can data log and test everything 😏
Engineering Explained off topic but as video suggestion how much would you need / calculating for parking lot A/C or heating to work with only a battery? I tried finding it but to no avail
I do have numbers for how much all of the equipment can consume @ full load in kWh but that’s different from “ just maintaining temperature deltas “ aka outside is 110F and I’m asking for less than 75F inside the car and by the way this might be a good companion video to tobitda Vinci video on Tesla model 3 battery packs specifically is it more efficient use seat heaters ( Peltier device type and efficiencies ? ) or the main cabin heat exchangers for heating / cooling or a “ cool shirt “ with a ice chest and water Plus which is faster for the job?
That 4 split screen explains everything with one picture
Many petrolheads I know and I'm one of them, do like to do economy driving. We have a simple system where we try to get into higher gears ASAP and keep the rpm below 3000 WITHOUT lugging the engine. I have a Honda City, which can be quite comfortable even below 2000. Infact, what we are doing is exactly what Jason says. Load it as fast as we can and keep rpm low, and NEVER ever brake (unless you relly need to, cause braking is waste of fuel). Try to coast near red lights and crossings. Blasting through highways and backroads is fun when you got loads of fuel, but can get real interesting when you are low and filling stations are far. Jason explained it engineeringly, ofcourse!! Thank you for another great video.
Awww.. thanks buddy :-)
It's too bad my MY17 impreza only has 5 gears and highway cruising speeds are right around 3000 rpm.
Hi Tracey, that CAN be a limitation.. But 3000rpm is still pretty good, and you are definitely gonna see gains.. Rather than cruising, most fuel is wasted during stop and starts like heavy traffic. A long time back "overdrive" gear used to be installed for this very same reason. Many people thought it was for going faster, but it was to keep rpms low at highway speeds. Engineering Explained will probably do a video on it pretty soon!! Safe driving Tracey :-)
My Fiesta ST has 6 gears, but also cruises around 3-3,5k RPM on the highway :(
If it had 2 more gears, it would cruise around 2500RPM and get 40+ MPG!
@Ashwin: Do you prefer engine braking over braking with a pedal?
What would be great to see is a comparison of mid term fuel consumption at the same distance between:
1) faster acceleration with higher rpm and immediately after reaching the desired speed, shifting into highest gear and keep it rollin (= short time of high consumption, long time of low consumption)
2) slow acceleration in higher gears to desired speed and keep it rollin (= longer time of mid fuel consumption, less time of low consumption)
A balance between the two of them would be ideal
Hey Guys Help mePLease
I have altok10 1000cc petrol car from india ..I always used to keep 1000-1300 rpm So i thought i am theMOst intelligent person Onthis Whole universe 😅..My car is of 2013 cheap car . it dosent show fuel economy on odometre screen..So what economy i got so much years ? ..Car's 5th gear 2000 rpm is on 70km/hr speed ..why admin said 0.35 as early as possible and then said at 7.40 1500 to 3000..i Tested 2-3 times by tank to tank and it was 22Km/Litre with Ac. Company claims 25
In Austria you learn at driving school to keep the rpm as low as possible while driving, but speed up as fast as possible (to keep the acceleration time short).
THIS IS WHAT I'M LOOKING FOR
From my own experience the longer you take to get up to speed the more fuel my cars use. Shifting early prolongs fuel consumption by not benefiting from torque multiplication and spending more time loaded. I coast a lot but take off pretty fast up to speed and I average between 3-4mpg better then rated on most the cars I drive using that method.
High load low rpm = Miles per gallon
High load high rpm = Smiles per gallon
Edit: 1k likes?! Damn...
Haha I think you mean high load high rpm = smiles per gallon. Low load is fairly dull. :)
Engineering Explained Oops! You're correct! I'll edit that! :)
Low load High RPM: Engine Braking
Granny who drives 10mph below the speed limit in the left lane had to chime in I see.
"Noone should be passing me anyway im doing the speeeeed limit!"
Try that on the Autobahn Gramps, get your electrolytes up... Sad...
Dubz0Eight You referring to Chris Sun's comment? Idk I don't think he meant it like that, I think he meant it is unfortunate to get tickets when you're just tryin' to have a fun time (smiles per gallon) in your car. But I would agree that "gramps" hogging up the left lane is quite annoying, I see people doing that ALL the time.
For the best fuel economy, walking is pretty efficient.
Frouch Itude Mitochondria working at peak torque for the electron transport chain.
man out of time I almost failed my bio test don’t be so scientific now😂
Frouch Itude but vtec can’t kick in (yo) when you’re walking...
Bicycling is way more efficient
Vitamin B12 can kick in yo with the proper fuel..
i just learned to listen to my car, i learned to drive in a manual, if you listen, the motor will tell you when the best time is to shift up, as well as shift down
When ever I listen to my car It goes braaaaaaaaaaa next gear braaaaaa
The right time to shift depends entirely on how you want to drive it. You can always accelerate slower and rev lower on the way up, or drive faster and rev higher. Just make sure you match your revs to the tempo you want to drive at. If you keep it revved low while applying lots of throttle you're doing lots of harm, and if you keep it revved high while applying very little throttle, you're going to get more engine drag from the revs than you're delivering to the drive train and are just throwing gas in the toilet.
Of course there's a sweet spot, and you need to adapt to conditions. The more drag forces are on you, the higher you should be revving before switching as well. If the road is torn up vs a clean pave for example. Going uphill vs downhill also, of course.
If you always listen for the same sound all the time you aren't adapting to conditions and probably driving poorly a lot of the time
Shoot .... I guess that means I have to ditch the stereo 😁
0:35 - “As early as possible”
Okay, bye.
was going to say that haha
Why is that?
@Nigel Are you saying that an engine will labour less if it is routinely revved higher than needs to be?
@@Cpt.Phenom there is sweet spot. Lugging the engine can be just as bad if not worse than high revving
@@Maroco918 I'd rather shift slightly late and burn a bit more gas than lug the engine and potentially damage it and/or the transmission.
1:00 “there is roll resistance from the tires” well... you can always take them off.
One day...
Most of the rolling resistance comes from the tread. Once the tread is worn down, you give the tires another 10 psi all around, and you're off to the races, so to speak.
I drive on 3 tires for weight reduction anyways
Well thar is what trains did and they do get much beter fuel economies! Just don't try and turn
I did this and now my rotor dust cover is bent
Short version, keep it low rpm between 2k and 3k at whatever gear you're in. If you pass that it's time to shift.
Now if you're a racer or you want to accelerate a lot, you usually go higher rpm before shifting for power delivery bc you need to get as much juice from each gear/rev as possible, but not go too high or you'll start forcing the engine and just waste power delivery.
going above 3k in a diesel is usually unnecessary, they achieve peak torque at around 3k RPM
@@Menon9767in benzin you shouldn't go above 3.5k even for power and for efficiency of motor durability and fuel efficiency don't go over 2.5k on any gear, 3k is also somewhat ok
@@davolthe1261 sure for fuel efficiency, but if you want peak power you gotta hit at least 4-5k
It depends how much load you need. Is it more efficient to go round a car park at 3000 rpm in 1st instead of 2nd or 3rd? No you barely need 1000 rpm to go round a car park. 3000 rpm is enough to go on a motorway, so scale the rpm with the power you need. If you are really feathering the throttle and just rolling around urban streets you can shift up at 1500 rpm. If you need to climb a hill, 3000 rpm might not be enough.
It's hard to measure load though as most cars don't have a torque meter, but as a general rule shift down if you are exceeding about 80% of available torque at rpm exceeding 2000 or 50% available if at 1500. Below 1500 only use a smaller % of available torque. Back off the accelerator or shift down if you are needing too much at low rpm.
In a nutshell:
*As soon as you can without bogging*
Yep. Pretty much how every EU taxi driver drives.
Paul Taylor accurate.
+Paul Indian Taxis just keep bogging lmao
Yeah, I remember reading that in 1981 in a "Das Auto" article about fuel economy. Old Idea that still works in most cases. EE said it right, as long as preignition does not occur.
Yup the short answer, shift as soon as possible. Other points would be: 1.dont accelerate while in high gear/low rpm, 3. Let go of the gas pedal while going downhill, 4. Dont use highways they ruin fuel economy...of course this advice is for granny drivers 😂😂😂
I shift when my car asks for it, with sound.
Q: What's it sound like when you're doing it wrong?
A: Bang! And Olufsen!
same :/
Yeah, my car says "vom, vom, vo---- please shift me"
My older brother taught me how to drive manual transmission. He also taught me to shift by sound of the engine also... if it sounds like the engine is going to explode shift up, if sounds like its going to die, shift down low.
me too, mainly because my car don't even have a tacometer hue(in reality after driving the same car for a long time you kind of feel when you need to shift).
I'm driving from 1500 to 3000 rpm in hopes that it will give good fuel economy and it turns out that it actually does
thanks
You mentioning BSFC few videos back changed my driving style and lowered my fuel consumption some 10% more (now reaching 50mpg with 2003 3-cyl 40kw 1.2 liter gasoline). Thank you for that. While you are at it, you should mention pulse and glide driving style that is closely connected with BSFC. You need to know and understand BSFC to understand PnG. I am really happy you care about fuel economy among other things.
Awesome, very cool that you've seen an improvement in your fuel consumption!
Dude, kW figures in Engines are work
@Jay Barker
If your electrical appliances are consuming power and producing no apparent work, then most of it is converted to heat. Did you know that electric heaters are 100% efficient?
Assuming I have 40kW capable engine and its thermal efficiency would be 40% (which is way too high for a gasoline btw), then I could say my engine CONSUMES 100kW in fuel it is using when producing full 40kW.
BSFC values are in g/kWh and if I knew the kWh hidden in one gram of gasoline, then I could calculate the thermal efficiency map from BSFC map (I guess).
A kilowatt (output) is 1000 Newton force moved 1 metre in 1 second. If it required 200 Newtons (around 20kg on earth) force to push a car then 1 kilowatt would take it 5 m/s or about 11 mph. It is around 1 and a third horsepower.
Obviously it will take more fuel burned because of wasted heat energy in an engine, which only converts about a quarter of the energy to force and movement (better or worse depending on load and RPM)
Of course, there are different energy and power consumption that is measured in different ways. For example you could have kCal per second or BTU/second, which are defined by raising the temperature of water a kCal is raising a litre of water by 1 degree Celsius. A BTU is raising a pound weight of water by 1 degree Fahrenheit.
You can in fact convert between mechanical and thermal and there are 4.1855 kilojoules (1000N 1m) in a kCal.
With an audio amplifier, there will be thermal energy lost in transformers and microchips and then a set amount of electrical power delivered to the speaker. Of the electrical power delivered to the speaker, a lot will be lost in heat in the voice coil, a tiny bit lost in the cables and also some in the surround and spider of the speaker. The rest is transferred into mechanical energy in the air which is what you hear as sound, and even that becomes heat eventually when it has echoed round the room a bit and absorbed.
The actual "wattage" in terms of force x distane over time of air compression is quite low (e.g. the amount of force compressing the air x the distance the air atoms moved/time to rearrange the air compared to silent still air), with even a single watt being as loud as a rock band at full bore, maybe taking as much as 100 watts from the speakers to do this.
The coal burned to run the 100 watt amp might be as much as 400 watts back at the power plant, so your coal to music ratio isn't that good, although thankfully it doesn't take a lot of power to get LOUD.
It's true that thermal engines are only about 25% efficient. I've heard for the bugatti veyron, its 10 radiators are to chuck out the 3000 horsepower of heat along with the 987 horsepower of smiles when accelerating full bore.
We can work this out. I've heard that a bugatti veyron at max empties 100 litres of fuel in 12 minutes. Petrol is 31.5 mJ per litre so 0.1389 litres a second is 4.375 million watts which is 5864 horsepower, so a bugatti veyron is only 987/5864 = 17% efficient?? Perhaps maximum rpm is inefficient though. There might also be some unburned fuel or partially burned fuel which is inevitable.
An electric heater is 100% at converting electrical power to heat. Guess what, so is a light bulb. The light gets hot, and the light that shines is absorbed by you and the furniture and turns to heat. So are most other appliances. A television has parts that get hot and heat comes out the back. The picture of the TV is light that is absorbed by the room into tiny amounts of heat. The sound of the speaker(s) is absorbed also making small amounts of heat. A kilowatt TV (which would probably fill a whole wall it would be so big) would warm the room nicely whilst you watched, and awaited your electricity bill if you watched it a lot. So if you're feeling cold, and the house is a mess, you may as well vacuum the house to make heat.
The exception is a battery charger which stores energy as chemical energy, until you use the energy in the battery for more heat!
If the electricity comes from a coal powerplant it is not efficient though because you are turning heat into electricity and back, delivering less than a quarter of your energy back if you count conversion and wire losses. You may as well burn something like gas to make heat because the chimney losses are less than the power plant losses by far.
instructions unclear, constantly bog my engine in 5th gear up hills
Uphill = use lower gears & accelerate
@@stefaneduard8169 he's taking the piss out of how simplistic this video makes shifting seem, and can cause people to drive under revved
Funny, but my car goes uphill on highways in 8th gear. Just adds a little boost.
While i agree with you, there needs to be a caveat. Different engines have different power bands, Straying away from said power band too much, can ruin your mileage. I used to have a Mazda B2200 truck, 2.2 liter 5 speed, it liked to rev and averaged 25 MPG running in the 3,000-5,000 RPM power band, for acceleration. I sold that truck to my dad and he lugged it everywhere and only averaged like 18. asked me how i was hitting 25? I told him to treat it like a bike, rev it and let it run. He tossed me the keys and said, show me how you drove it. When i did, he was amazed it even got mileage, but he replicated my driving style and it instantly got 25 MPG all day every day till he got rid of it.
You are right to a point, but the engine has a specific area it likes to and was designed for. if you stray too far outside that comfort zone it can hurt you both in mileage and also durability, because Spark knock is no joke, it'll ruin your engine bearings.
Every engine has different BSFC map, but usually similar to the one Jason has shown. The best way would be to measure your own exact map using probably OBD2 data (assuming the car has OBD2 connector). It is on my personal to-do list.
In "ecodriving" courses, it's taught that in constant speed, use the highest gear where the engine runs well (not lugging). This is consistent with your advice. Now, another interesting question is what to do when you're at a stop light at standstill, and you're going to accelerate up to let's say 70-100km/h. Then the advice is actually to accelerate fairly hard to get up to speed quickly, so that you then can use higher gear for longer distance. You didn't touch on this at much (actually the title of this video would better have been "what gear to choose when driving at constant speed"), but I think it's an important topic. Some people think it's fuel efficient to slowly accelerate, but this just keeps them longer in lower gears which is not efficient. So the advice for best fuel economy is to put in quite a lot of throttle (probably in the 1500-3000rpm band you were talking about) to get yourself up to desired speed, and then choose the highest gear suitable for that speed. Then another thing for fuel economy is to avoid using the brakes. So coasting is important, if you see well ahead that you're going to have to reduce speed, get off the throttle early, and coast in gear. On petrol engines, this cuts off the fuel supply completely, so as you're coasting, you're using no fuel. This means from highway speeds you can get approximately a kilometer of "no-fuel-used". I see way too often people maintaining speed almost up until the stop light or whatever, and then get on the brakes.
en.wikipedia.org/wiki/Energy-efficient_driving has lots of these things.
Exactly. I have tested this on a petrol car, and the acceleration style you mention was measurably more efficient.
Diesels seem less happy.
Yeah, my thoughts exactly when I saw this video. I always accelerate quickly in a lower gear to get up to speed and then get into highest gear (usually 50 to 100 km/h in 3rd and then immediately 6th). It takes a few seconds and a bit of fuel, unlike other people that take forever to accelerate in higher gears and shift way too early (often even below 2500rpm, with a gasoline engine!). I hate being stuck behind such people because they ruin my fuel economy as well as theirs!! :D
Wouldnt that kind of driving increase the temperature too fast and put strain on the head gasket? Especially when you start driving in the morning after the car had been sitting in the cold during the night...
If the engine is cold then of course you should not rev it. What we're talking about is what to do after the engine has come up to something resembling normal operating temperature. We're also not talking about flooring the accelerator, we're talking about accelerating "firmly". In most cars this would involve using perhaps 50% of the available power (for normal cars, not sports cars), typically getting up to cruising speed in 13-15 seconds perhaps. So not flooring it, not revving to redline, just get up to speed in a comfortable short time. Some people will take "forever" to get up to cruising speed, and this is not fuel efficient.
Haha that would make so much sense as to why whenever i put resume cruise control on my grand marquis (lets say was 60mph now at 40) it freaking just steps on it.
After all this engineering explained my brain is spinning at very high rpm right now.
Time to shift!
@@EngineeringExplained Yeah, exactly :)
ikr their could of been a easier way to explain it rather than a 7 minute video
whats good then it would be harder to understand. Sometimes it helps to pause and look/think about what was said. What made it most hard to understand (for me personally) was the pace he was speaking at. I had to pause a few times to catch up
@@nicholasbolton4554 yup i couldnt keep up, i watch youtube all the time but 4 some reason i dont seem to understand this guy most of the time
the red dude at 6:34 had pretty good fuel efficiency
Ben Goyette q
That guy measures his fuel consumption in "miles per sandwich" instead of "miles per gallon".
Dustin B LOL
Still doing enduro?
sneakyb always!
When you own an s2000 its 9k every gear!
Darzy NO.
*slaps you with maintenance schedule*
NO.
*slap*
NO.
*slap*
yes--I MEAN NO
yeah it's def 9k each time. It's a Honda, it'll do it all day no problem.
It's over 9000!!!
VTEC
Certainly is.
I bought a Rav4 lately. 2004 y. 2.0 petrol 4wd. Friend told me that it's thirsty, around 12L/100km or so. Well. I've driven it about a week and my average is 7,6L/100km atm. Oh yeah I did throw one rear seat away.
When you see the smoke, it is time.
To get a new car?
😂🤣😭
I spend 80-90% of my daily driving in 5th. Although when people decide to go 10 mph under in town, I tend to be in 3rd or 4th. My 86 gets amazing gas mileage and it's a blast to drive.
Human Being agree man best car out their
Measurements at 58mph are an odd choice for determining "when to shift", a decision one makes when trying to get up to 58mph. I was hoping to see the differences between shifting at, say, 2500 vs 2000 vs 1500 rpm.
Shift at lower rpm without it straining/stalling the engine. I drive a diesel so almost impossible to stall I can actually (on a flat road) go through the entire trans to top gear at 30mph
That example was about fuel economy. The concept can be applied to determining when to shift if you’re concerned about fuel economy (shift as soon as possible without lugging engine). The test you would have liked to see would show the same thing, but would have been much more annoying for him to conduct.
Yeah, that example is pretty ridiculous. I can switch to the last gear at 30, at 58 there isn't any choice
It is written in the manual of my car, at what rpm should I shift to be fuel efficient. It actually translates into "as early as possible", as Jason said.
Finally someone to answer this question. I’ve been debating this with a friend of mine for over 20 years about this.
He insists that keeping the rpm as low as possible is better efficiency
I always said shifting at the peak torque point is better regardless where that is in the rpm will be more efficient.
Looks like i owns him a Coke
Peak torque doesn't necessarily correlate with the best BSFC, but it often is the spot with the greatest volumetric efficiency. That's intuitive, since the region where you make the most torque would likely be where you pull in the most air, relative to the size of the engine cylinders.
Kristopher Klassen I don't agree with higher gear statement. I offten get higher fuel consumption on higher gear and not accelerating, just steady right foot. It may be car specific and also different elevations lead to different results.
You're saying I need to shift at 4850rpm lol
i used to shift at 2500 on my NA 1.6l inline-4 and it felt very sluggish and returned about 11L/KM, now im doing 10.2L/KM shifting at 3000 except on a descending stretch, where i shift at around 2200.
Kristopher Klassen. Engine should be rev happy by apllying no more as 30% of throttle, And there comes to play in how RPM you should change gears. Engines, Cars, And gearboxes Are diferent. Nothing absolutely Universal doesnt exist. But that 30% throttle rule simply rules 😁
Experience from 40 years of driving taxi driving in Sydney, Australia. Mostly in approximately 4:0 litre, 6 cylinder, automatics. Lights change to green, give it a bit of a boot - again, a bit of a boot - then back off. The gearbox will find the highest, practical gear, by it's self. When I drove my own, Falcon GT manual, in suburban areas, I used to skip-shift a lot.
I don't have words to express my sincere gratitude for you bro .... Thanks a lot for spreading awareness....
When to shift?
When the car starts shaking
or when the engine sounds like its struggling
lmao
7:43 that's all you need to listen to
thank me later
Thank you, I didn’t have to watch the whole video for what I already know
Why can’t I just thank you now? 😉
I watched this a couple of weeks ago, so thank you
Thou art the man
My hero
If you live with LA traffic and drive manual, you are already obsessive about this subject.
Or NYC
Hahahah yess
Or hating the manual life in traffic.
Manual is only fun on a winding road.
If I hit the highway, I use an automatic.
Scott Dann
If you're driving on a highway, a manual is basically an automatic. There are very few cases where you will need to downshift past 4th.
Before VTEC kicks in! Seriously though, if I hit vtec at all in my GSR, the fuel mileage would drastically decrease.
Engineer here.
- when going at a constant speed, use the highest gear you can for the lowest RPM
- when accelerating, use the RPM ranges that has a higher torque/RPM ratio. Look at the RPM/torque graphs of your engine (the dyno tests give you these), and select the last RPM point, where the graph is at a 45 degree increase. That will be the recommended maximum RPM.
Derively lmao engineer here
BMW drivers didn’t like this.
Lol 🤣
Why?
I love comments about BMW drivers. Do you drive a BMW?
Leonardo Colella car make vroom vroom noise in late/low shifts
Honda also
I'm always amazed by how smooth your presentation is while you're driving... If I'm driving around curves, I usually stop talking or repeat myself or go "uhhh" a lot
60mph in 2nd gear would destroy my car 😂
What do you drive?
@@nathanvanpelt7216 why would it destroy his car? I don't have car neither do I drive and I'm a noob
@@JarmalK just that a real spinny boi makes for a heckin lot of heat n rubbing. Which may shave down your cylinder wall and let the floaties hang aboot. which to your engine feels like running on a beach with sand in yer crack. Its hott components also grow thrice its size, like the grinches heart. And then stuff dont really line up as awell. But EE is a gangster and doesnt play by the rules. Gets results.
@@nathanvanpelt7216 lol okay thanks bro ig
60mph in 2nd wouldn’t destroy my Jeep, just its engine. Especially since it’s redline is 5500rpm.
Your test is kind of incomplete because you tested the coasting efficiency of each gear but didn't test the differences of efficiency to reach that speed under acceleration. If the goal is to reach a certain speed, it may be more efficient to do it quickly with less duration of load rather than slowly while being under throttle for a longer amount of time. I'd really like to know where the balance is.
To get your car down the road the most efficiently you want to produce the power needed at the highest efficiency. It doesn't matter whether that power was used to accelerate or maintain speed. Jason makes it clear that the highest efficiency for most engines is between 1500 and 3k rpm and full load, meaning at cruising (low rpm low load) or at brisk acceleration (high rpm, high load), your efficiency is worse. Why would you want to take a long period of high efficiency and replace it with a shorter period of slightly worse efficiency followed by a period of even worse efficiency? A second good point is that accelerating faster, you have a greater tendency to 1) overshoot your desired speed, which is not advantageous for economy or 2) have to brake harder if, say, the next light turns red.
@@tscook10 you're looking at this from more of a broad physics perspective than a car physics perspective. Saying most engines are efficient between an arbitrary rev range (pretty wide one in the eg) is too much of a blanket statement. You could have two of the same exact engine running different fuel maps and ignition timing and that claim could easily be made untrue. And the coasting efficiency would end up the same after the target speed was reached, as the car would be shifted into overdrive, so it's irrelevant.
@@Shakshuka69 , I agree, when speaking in generalities we can't be specific but I think it is important to note that the vast majority of production cars, in stock form will be most efficient at some specific speed between 1500 and 3k rpm and that above that speed they get less efficient. The exact shifting point for peak efficiency will vary by car to some degree. However, We've already established that accelerating at peak load will br more efficient than part load and if you're asking whether it will be more efficient to shift at 3k rpm or 6k rpm I would say, with very few exceptions in the automotive world, that the former will be most efficient.
This is something I was hoping he would have touched on. While everyone is stating the engine is most efficient in low rpm high load, the vehicle is most efficient in the highest gear. So although the engine may be most efficient in any given instant running through the gears as quickly as possible it would probably be more efficient to accelerate quickly and get to the highest gear as quickly as possible. A perfect example of when this technique is likely more efficient would be something like a high way on ramp. I’m glad you brought this up and wish engineering explained had covered the concept of rush to idle because as it sits this video only discusses where the engine is most efficient and not when the vehicle is most efficient. Ironic consider he briefly acknowledges that he’s not really discussing fuel economy at the end of the video.
Shifting as early as possible during acceleration will put you in the highest gear possible at any given time. Combine this with the fact that, typically, engines are most efficient at low rpm, then it follows that the most efficient way to accelerate is to shift as early as possible without lugging or possibly a bit later if the efficiency peak is particularly high in the RPM range.
I kind of always figured this was the case, but it is very cool to see the details behind it and an actual test!
Its too bad that he actually proved "Use the right gear for your cruise speed" and not when to shift.
Same here, lower rpm also means less wear of the various moving parts of the engine.
With gas being $5 a gallon, I wanted to double check that I'm shifting efficiently! I didn't know this, fairly new to driving manual. Thank you!
I usually shift below 3k rpm on a normal driving.
Yup, that's generally correct.
I usually shift somewhere around 1500 rpm.
Diesel life.
I usually shift at 2k no more ls2 engine
cl4ster17
Depending on the generation of diesel you're running, that might not be optimal as you may be increasing your maintenance bill in the long run. Older diesels tend to get the turbo and the air paths clogged with sooth if you are mostly out of turbo boost. Also, if you're always at low rpm, high load, your flywheel may suffer as the vibration is increased.
Older diesels, such as the VW's 1.9TDI run best when shifting at ~2500 rpm. Yes, your MPG may decrease, but the amount really is insignificant. However, newer diesels are designed to run as much as possible at low RPM to reduce fuel consumption.
I shift at 2500 rpms unless I want my vetch to kick in .
I don't even have a car, but I've watched as much of your explanatory videos as I could! really interesting stuff! thanks!
I don't always agree with Jason (see Mercedes Clever Turbo Engine), but as a mechanical engineer specializing in internal combustion engines, I think this video hits the nail on the head. Don't over rev the engine, but as you accelerate shift into higher gears at lower RPMs. I own a Cadillac ATS 2.0T with a six-speed manual transmission. It's rated at 20 MPG city and 28 MPG highway. Over the last 45k miles, I have averaged over 31 MPG overall in mixed driving -- more in the summer and less in the winter. (Yes, I record everything.) It's not difficult to do. Jason's comparison at about the 3:40 mark in the video is excellent. And, yes, BSFC and MPG are different concepts. Now, let's do this same video using a car equipped with a Diesel engine. (Note Diesel is capitalized because it's a person's name.) Good video.
In my 6mt forester I noticed I can shift into 2 at 20mph, 3rd at 30 mph, 4th at 40 mph, 5th at 50 mph and 6th st 60 mph. I discovered this after plugging all my gear ratios into a spread sheet. I wanted each shift to drop the rpm to around 2000 rpm. I then noticed that each shift brought the mph to near what the gear number is.
2:48 How can you do that. Talking that complicated while driving
Haha, the '16 Crosstreks are actually rocking auto-pilot and I'm just pretending to drive. ;)
Haha. I knew it !!! So, the stick is a fake
He's an engineer too lol
Yathu prem He's a videographer trying to tell a story. Not everything has to be sequential or in real time. I'm not offended by that but it amazes me how many are.
Cause he's smart and understands what he is "explaining"
Modern cars have shift recommendation displays that you can use as a guide. Economical means accelerating quickly to the desired speed, shifting up as early as possible and driving with foresight. The most economical speed on the motorway is between 80 and 100 km/h (50-62 mph). Speeds over 140 km/h (over 86 mph) should be avoided because the cars consume above average fuel due to air resistance.
I drive 60 miles a day on highway and here is what I found.
1) be in max gear.
2) drive close behind semi trucks or any slow and large vehicle.
driving at 54 mph (90kmh) is usually where cars have the highest MPG.
BUT air resistance is taking the numbers down, thats where following trucks is important, they create a depressurisation behind them, see them as boats and try to stay in their wake.
now, keep a safe distance, but keep in mind that trucks dont brake as hard as you can
Yep. Anyone who has ever ridden a bicycle close behind a large bus knows. You can get up to very high speeds with no effort at all.
You kinda ignore something important here. Throttle setting during acceleration. You're actually using up most of your fuel accelerating, and here's where I see most people screw up. For some reason people think gentle acceleration makes for high fuel economy. Starving the engine of fuel never allowing it to get to peak efficiency...
Imrahil its funny, i have a first gen miata and have done back to back fuel economy test. accelerating hard and blasting around town gets almost exactly the same fuel consumption as accelerating as slow as possible.
im not saying your wrong tho. It shows that cars dont like accelerating slow. doesnt help consumption at all.
Discussed this quite a bit in the video. Higher load tends to have better efficiency. Higher throttle = higher load.
I own a second generation Miata and experience the same thing. Shifting early (below 25kRPM) yields less miles per gallon than at 3-3,5K RPM in practice. And is less fun ;). It seems they reward a quick (but not mental) driving style.
@Engineering Explained Our Mini Cooper S 2014 has fuel economy digital gauges built into the dash when the driving mode is set to 'eco'. What I noticed is that these gauges seem to show worse fuel economy the more load is on the engine, irrespective of engine RPM. Are these gauges incorrect? The video suggests lower-medium engine load is required to achieve good fuel economy, as long as revs aren't too high. But I'm pretty sure that loading the engine at say 30-50% at 2000rpm gives a worse result on the gauges compared to say 20% load ('load' meaning throttle position more or less as I have no other way of measuring it). Sorry if this question sounds complicated but I'm curious. I have not tested this using the real time fuel economy figures of the trip computer. I wonder if those would tell a different tale to the 'eco meter' gauges I'm referring to.
+9000Redline That's probably because it's using a small amount more fuel per metre at higher load to produce a significantly higher amount of power at the crank. Practically this means that you'll be accelerating during this high load scenario until your speed increases and your losses to aerodynamics outweigh any efficiency gains, but it also means you can get up to your desired speed quicker where you can reduce the throttle, using less fuel overall.
Try this (if you're in a car with a manual box and have a long empty road): If you usually do 100km/h, accelerate at high load (~70% throttle) until you get to 110km/h, and then shift into neutral. At idle, in neutral, the engine and gearbox friction is minimal, and so you're using very little fuel. Once the car reaches 90km/h, put it back into gear, and again accelerate until 110km/h, putting it back into neutral. While doing this, If you've got a passenger, get them to periodically take fuel economy readings (once every 5 seconds or so, even when in neutral and coasting). See if these values average out to more or less than a reading taken at a constant 100km/h.
Gotta say, switching gears around 2500-3000 rpm always results in such a sweet low end exhaust sound. 🤪
And switching from 1st gear to 3rd gear, skipping 2nd is another way to be efficient. I usually don't even use 2nd I build rpm on 1st quickly, jump to 3rd build enough to get me through 4 "faster", and I then switch to 5th and remain there till I build just sufficient rpm to get to 6th for cruise.
So basically, I've been doing it perfectly all this time.
Still great to know.
Hey Guys Help mePLease
I have altok10 1000cc petrol car from india ..I always used to keep 1000-1300 rpm So i thought i am theMOst intelligent person Onthis Whole universe 😅..My car is of 2013 cheap car . it dosent show fuel economy on odometre screen..So what economy i got so much years ? ..Car's 5th gear 2000 rpm is on 70km/hr speed ..why admin said 0.35 as early as possible and then said at 7.40 1500 to 3000..i Tested 2-3 times by tank to tank and it was 22Km/Litre with Ac. Company claims 25
Best economics....slow down wenn you see the police....no tickets! 👍😁
thank you! I actually dropped my petrol consumption from 9l/100km to 5l/100km thanks to this video
When I was learning the mandatory echo driving I was instructed to accelerate as quickly as possible in low gears and skip a gear when I get to cruising speed. For example, if you are approaching an intersection you slow down as usual. Then when you are in second gear complete your turn, you quickly accelerate up to speed and go straight to 4th gear. I was told it uses up to 80% less fuel than accelerating at a normal speed and not skipping gears.
I don't know if it's true or not, but it is in my muscle memory now and I still do it.
if you skip to the 4th gear you dont use the 3rd, which is kinda bad cause u don't wear it out making it uneven with the gears. (hard to explain, english is not my native language sorry)
I drove my 1999 Honda CRV manual for over 8 years. Over time, I figured out that 2500 RPMs was the sweetspot for MPG. when I drove it, I keeped it around 2000 RPMs when going downhill and 2500 RPMs when driving Flat. It also made the car great for sharp back roads because it also has a short transmission because 2500 RPMs in fith gear is 50 MPH (which is also when it got its best fuel econmy of 28 MPG). Also, I learned if you want to get up to speed quickly for some reason, like going up a hill to merge on a highway, then you shift at 4000 RPMs. Any higher than that then your going to start buring a lot of fuel, any lower than that then you will be in fifth gear to quickly and not have enough power to get up the hill!
Hondas really love to rev at 4k
I was going to ask "what if you don't care about fuel economy but only want to accelerate as fast as possible?", but then you addressed that very topic in the second half of the video AND mentioned that there's a separate video dedicated entirely to that. Great video and channel!
A few other things to consider: Gasoline engines run most efficiently at the RPM of maximum torque which is around 3,000 RPMs for most 4 cylinders, give or take around 500 RPMs. Accelerating at wide open throttle up to around 3000 RPMs before changing gears I've found gets me the best gas mileage. Although I rarely accelerate at wide open throttle in first, it's a bit too dramatic in a rather fast car. :). At wide open throttle not only do you have a lot less vacuum in the intake resisting the engine but the intake air rushes more violently into the engine giving better mixing of the air and fuel, giving a better combustion efficiency. This increase in combustion efficiency is part of the reason torque goes up so noticeably around 3,000 RPM. The other reason is the air velocity in your intake runner hits just the right point to do a little supercharging of the cylinder. My driving style is to stay at wide open throttle as much as possible but not going over 3,500 RPMs too often. I like to accelerate up hills WOT in 5th and then coast down hills. My car is rated around 35 city/40 hwy, but I average 47 in the summer, 44 in winter. I'm not a slow driver either and I get up to speed quickly even though I shift early because I have a rather fast car with a light weight flywheel, 135 hp honda crx(2000 lb). I coast to stops a lot as well.
@Richwell Robles I tried this driving style in a 2007 Honda Civic with an automatic transmission. I can't go wide open throttle or the RPMs go too high. I can barely push on the throttle at all which really sucks. However it does coast very well when taking your foot off the gas and I can still use that technique. It would be a lot more efficient if you had to go to about three quarters throttle before it would downshift. I average between 35 and 38 miles per gallon in that car. I think it's supposed to be 32 in the city and 36 on the highway.
"shift up as early as possible": off course.
But my question is always: how to safely determine what is "too low".
I really like to roll near idle speed. How to determine when a (bigger) engine is suffering from low RPM? (below idle it's gonna starting to jump, that's clear.)
You will know; it starts jack rabbiting or you can clearly hear it ping. So what you do is teach yourself how you engine works by gradually trying how much throttle you can apply at increasingly lower rpm. In my my car I can safely do 3/4 throttle from 1100 RPM in 5'th gear, that is when I'm only going 25 MPH. That way my accelerations are fuel efficient from that speed and accelerating further to 30 or 45 from 25 in 5'th, gives me a mileage of 40 MPG. If i did this in 3'rd and 4'th I would be in the 25-30 MPG range while accelerating.
For my engine, the manufacturer says to always be above 1500 RPM. However, being an inline 6, the engine is very smooth from idle to rev-limiter, so I often find myself accelerating in 3rd gear at 1000 RPM. Of course, I do not go full throttle from those RPMs. If I need to go full throttle, then it means I need a lot of power, which, in turn means, I'm definitely in the wrong gear :)
Manufacturers don't recommend it but that is because they don't want you to lug the engine, which is to hard on bearings and piston rings, but you are not doing that, you are easy on the pedal at first. A test you can do on a piece of flat secluded road is to lift the foot from the accelerator at slow speed 25-30 in highest gear and note of which speed is settles down to ( you basically drive at idle RPM). Then carefully apply throttle in a way that increases your speed but does not strain the engine or make it bounce and you will notice as the speed slowly creeps up together with the RPM, you can safely apply progressively more throttle, and 1600 RPM sounds about right as the speed where the engine regains it normal responsiveness and you can apply more than half throttle without problem. In my car I can apply full throttle from 1500 if I wish. You basically want to feel as sluggish as if you car was overloaded full of garden tiles. Careful on the throttle and be in top gear from 20-25 or what is possible with your car until you hit 30 and can accelerate normally. That way you'll use the least fuel to get going as the car needs to fire the fewest number of cylinders to get you up to speed. You can't do it if traffic is too intense, other drivers will go nuts on you. You probably already do it occasionally when starting in second by mistake and don't bother to shift down, just being extra careful on the pedal until you get up to normal second gear speed.
Yep, I do all that :) If I'm going at constant speed, I'm usually in 5th at ~40 mph. My car has rather short gearing, so, at that speed, I'm turning 1600 RPM, but as I mentioned earlier, I don't necessarily follow manufacturer's indications. I just make sure to load the engine in accordance with the RPM.
Everyone keeps recommending a certain RPM when shifting but here's my best advice:
All cars are different - gear ratios and engine torque;
Simply find that point where your car doesn't jerk in between quick upshifts while taking note of both the RPMs and the upshift speeds you are driving at.
When you engage the clutch a bit quicker than normal.. you can tell when you've found that point where the RPMs/engine speed matches the drivetrain speed as there is little to none RPM drop once the clutch has fully engaged on the higher gear and you can definitely feel the silky smooth shifting (2 finger shifting) without waiting for the synchros to slot the gear lever in from a lower to a higher gear. (faster clutch in and slower clutch out but a little bit quicker)
For downshifting, just memorize the speed where you upshifted for all the gears so you can downshift a bit faster (less clutch hanging or none at all) you can save your clutch with minimal wear and you don't have to rev match the engine if you're not on a spirited drive.
Save additional gas and clutch usage by always giving distance to the person in front of you to minimize clutch balancing in stop and go traffic.
I have found that this works best for me regardless if I'm driving a turbo V8 or a twin turbo inline 6. I'm getting 21-27 mpg in the city which isn't bad in my opinion.
Hope this helps y'all (:
minimal brakeking max coasting max gear at low 🤣🤤
modern small turbo engines thanks to higher torque at low rpm allow early shifts, which translates in amazing efficiency if you know how to drive. I can run under 1500 rpm all the time if i really want.
CivicChina not mine, at 1500rpm it feels sluggish it seems most happy between 2000 and 2500rpm. This is the Renault TCe 90
for deaf technical antitalents & masochists its ok :D
is it 90 hp? it can't do miracles, I have twice the power and probably only a few kg more, so obviously your engine has to work harder to move the car.
My average speed is 26 km/h, i don't see the point of pulling 1st gear to redline while stuck in traffic....
I've driven all types of vehicle with anywhere between 3 and 16 forward gears, and when I started learning, I was told to change up as early as possible, and that served me well, because it easy to tell from the behaviour of the engine if you change up too soon. I have driven automatic cars, and 40 ton dumper with an Allison 5-speed, but I much prefer manual gears. I particularly enjoyed changing gear with a crash box and judging the right revs to slide into gear without any painful grinding noises.
I normally stop upshifting when I get to either fourth gear or sixth gear, sometimes fifth. Sixth gear is the highest gear I have for cruising at high speed on the highway and fourth gear is more practical for cruising at lower speeds between signal lights in town. In other words, fourth gear is my city driving gear and sixth gear is my highway driving gear.
I don't want to have to keep paying for gas how do I download more gears so it drives for free???
Install BonziBuddy (don't do it, it's spyware).
You can just download a new car everytime
Actually most HGV drivers have three gear ranges in one gearbox, which theoretically gives them 18 gears (6 individual gears, 3 gear ratios) - but most truck drivers will jump many of them, dependent on how heavily loaded they are and what kind of incline/decline they are driving along, as many of the gears in the whole set are so similar that there's no point using them all.
Fit perpetual motion machine to your car
Fit a nuclear reactor to your car
I shift when i hear the engine starts to rev to high, that's what I love with manuals, you and the car are one with each other
Great video, just you explaining very clearly. No music no intro, just content, I love it. Thank you !
Best fuel economy?
The slowest you can go, in the highest gear you can go without killing the engine.
1000-2000rpm and 50kph is a really efficient spot. Even if you're not in top gear, air resistance really kills your mpg, so its often better to switch to a lower gear and slow down.
Great video as always! Can you make a video explaining exactly what load is and how it is measured? I think I understand the idea, but I'd love to learn the details and physics behind it.
best explanation for those who dont know car like me is > when the car is growling or right before it growls you change to higher gear, when the car feels like its having a problem or like its gonna stall or if its vibrating you go to lower gear.
No first gear at 60mph? 😜
Are you crazy? Lol
thesparksplug whoooosh
Redline it lol
Reverse gear is better, you got turbo sound too
Just put it in 'R' of race mode
I have a question that is perfect for Engineering Explained: Is it more economical to to a reasonably fast acceleration to the desired cruise speed or is it better to do it slower? The variables are interesting - the time spent accelerating being the one that springs to mind first. Hope you can make a video on this, if you haven't already. Great channel, by the way - I learn so many interesting things! :-)
I experimented with this quite a bit on long daily commutes on roads with lots of traffic lights, about 15 years ago. In my petrol BMW 318i at the time, I found that quick acceleration (not flooring it, of course) to the desired speed, was more fuel efficient than long, slow acceleration at low RPM’s.
All acceleration uses a lot of fuel. Doing it for a shorter time and distance is obviously better, provided that it isn’t offset by the difference in fuel consumption.
I could not replicate the results with the cars I’ve had since, all diesel BMW’s.
This is my suspicion too, but it would be cool to see some data on where the line goes between too slow acceleration and too fast acceleration. It may of course depend wildly on the car. I drive a Citroën 2cv in the summers, and it has a 29 hp 2-cyl 602cc engine, and full acceleration in that is basically a normal acceleration in a normal car (or even less). Spending 2 minutes getting to cruise is not useful, and I'm going to end up at high RPMs anyway. Maybe the goal RPM range is indicative of some of the variables here. Food for an engineer's mind, or what?
Jason basically explains it in the video, but you have to go one step further with the explanation. You want the engine to be at high load in the area of peak efficiency. For a lot of cars that's between about 1600rpm and 3000rpm. It doesn't really matter how long it takes to accelerate since the point of acceleration is to turn chemical energy in the fuel into kinetic energy in the car's mass. The only thing that tells you how efficiently that is done is: Break specific fuel consumption. It takes the same amount of energy to accelerate your car from x-mph to y-mph whether it takes a 10 seconds or 20 seconds (Let me put in right here that there is a heavy qualifier here that you are accelerating at some moderate pace at legal speeds where the amount of power accelerating the car is much greater than the amount of drag on the car, i.e. the amount needed to maintain speed, luckily, full load acceleration at 2k rpm and 5k rpm are likely within this range). Basically, the longer you can spend at the highest efficiency level, the better. Your cruising bsfc will almost definitely be worse than your accelerating bsfc, so why would you want to get to that earlier?
I play by ear and can even feel when it's ready to shift to the next gear. I barely or look at my gauges when to shift but that came with practice. You can even float to your gears without clutching which can save some wear on your clutch as long as know what your doing but wouldn't suggest it to beginners. Just practice and it'll become second nature.
I was just looking for a video like this!
Time to save on fuel when on the daily commute & floor it in the weekends to make up for all my savings haha
Right on time :)
I was taught to shift at 2000 rpm, works really well and is pretty quiet as well.
Same. Except for a few scenarios, like if i'm going uphill or when i'm carrying passengers or heavy load.
Agree, i drive a 2014 civic si, the rated is 31, i got 37mpg once for about a month, but i usually hover around 35mpg...i change gear at 2500rpm, this gives me enough power to pass 80% cars on the road
@Jay Leno I agree, but most of the small cars at 40mpg or 45mpg during that time were around 130hp would have been no fun to drive. The si with 205hp allows me enough power to switch lane quickly, plus the reliability of a daily, cant say no!
wow.. Real science and not just opinion. My modern VW's manual say very similar for fuel economy. The manual taught me a lesson though I was sceptical. I was taught to get into top gear as quickly as possible so usually revved high in low gears ... did that for years. with my new VW i was getting good economy with the old style of driving but after reading the manual i decided to give this new style a go. fact: noticeably better by approx 7mpg in urban use! worth doing in my experience.
I really don't think this video answered the question. It still needs to address whether to to shift early during acceleration to reduce fuel consumption or do it later to make the time driving slow and inefficient a bit shorter. Also how much throttle should the car be given. This is not truly explained, but only touched upon. I would like to hear an explanation about finding a sweet spot for how fast to accelerate alongside when to change gear.
That graph shows exactly that:)
shanecoleman. No it doesn’t. I have no idea why you would think that. I’m guessing you are not an engineer.
Castle Bravo Actually I have a masters degree in science. A lot more schooling than most engineers.
In a turbo engine I get a bit better gas mileage if I stay in a lower gear and not use turbo boost (air fuel mixture gets way richer once you start to lug the engine at all). So if I go up a hill in 6th I get worse gas then if I stayed at higher rpm in 4th or 5th and just stay light with the throttle
James Banks I wondered about this since I have a 2016 WRX 6-speed.
I kinda want to do some testing to see what kind of efficiency it is capable of. But the darn thing is just too much fun to drive fast!
why would you even want to go up a hill in 6th gear lol
honestly this guys super in depth and all but he gives u the best advice right away. Shift as early as possible. I hate to say it but its really that simple the rest of the video is just overthinking
I remember having an up-shift timing indicator light on my 1992 Ford Tempo. It seemed based on the manifold absolute pressure that depended on the load of the engine and throttle position. Also, the 1980’s BMW’s had a needle with a L/100 Km gradation probably linked to MAF.
Not only the 1980‘s bmw, my 2007 has that, so does the 2018 BMW of my mom…
Best time to shift gear for fuel economy ?
No problem ! CVT life bro
Assuming your CVT actually works as a CVT and isn't programmed to use predefined gear ratios just to feel more "normal".
Really want the best economy? Get a BEV.
Yeah, I can't stand when CVTs pretend to have gears.
CVT = :O###
That's puking for the old timers
CVT doesn't pretend anything. It just has excellent fuel economy.
Of course this is the basis of the old "Shell Economy Run" burn and coast technique. It's amazing what can be accomplished by this. When forced to make a 350 mile trip during the 2000 fuel shortage in the UK I got just short of 50 MPG (that's an imperial gallon!) out of an E34 BMW 525i by burn and coast (and tyre pressures on the high end of the permitted range). It felt like I was peddling the thing the whole way with all the into top, boot it, into neutral work required. Going back far enough some UK cars were fitted with free-wheels in top gear to allow this to be done without all the legwork.
Thanks this was really helpful!
But i have a question: Does this apply to acceleration aswell? You mentioned staying 60 MPH all the time which is quite self explaining, higher gear = lower fuel consumption, but what about accelerating to a specific speed and then shifting and holding the higher speed in the highest gear? Can you do some Tests about that too?
I shift gear when i can't hear my radio anymore 😄.
I cant believe this needed a video... its no shock lower RPM is going to give best mileage... NOTHING is more satisfying than being a manual shift driver, experiencing your first CVT. Its incredible technology. You can get up to speed on the highway NEVER going over 2k RPM's exploiting the full distance of the on ramp. And it just chills there at 70mph at 1.5 RPM. ITS AMAZING! In my V6, 6 speed auto Lexus Its 2.5 RPM at 70MPH, in my Altima its 1.5RPM at cruising. Im just amazed.
Always impressed by your deep knowledge, you turn something upside down that I was led to believe by a trusted source long time ago. Their wisdom was, accelerate as quickly as possible to your desired speed and when there go to the lowest gear still safe/comfortable. The idea was that acceleration in the lower torque and power region of an engine would cost relatively much total fuel, even when consumption during a brief brisk acceleration is very high. So you say this is not true? And I have been living with a lie all those years? I think I'll keep the old version to justify down-shifting with rev matching to a gear that gives me the beginning of turbo power, and floor it. And between 60 and 70 m/h put the car on cruise control in 6, with over 60 mi/ga economy. :)
In my automatic, I just ease off the gas pedal a bit when I want to shift early.
My ‘84 Peugeot 505 GL manual said that for the best fuel economy, shift into a high gear as soon as possible. That doesn’t mean to floor it, but not to dilly-dally in lower gears.
I do that in city driving ... I shift before hitting 2k RPM ... around 40-60 Kph ... in 4th gear ... and yes it saves fuel consumption ...
we want the same expiriment you did with a diesel engine this time!! to see how much of the benefit comes from pumping losses and how much from added friction!
That would be neat to do!
Yes, please do more on the subject of diesels. What about lugging them? Is detonation the intended working principle of Diesels?
Engineering Explained Would it be an old TDI VW. I don't know of any diesel cars on the road. Because America only has very few diesel cars. I think Chevy has a little diesel in their new Equinox.
you didn't test it while accelerating though
your test was on a constant speed
who will use high RPM on a constant speed with all due respect
Yes, but the test shows different conditions. The car goes up and down hills, where it has to accelerate to maintain the vehicle speed. We're demonstrating that BSFC is best at high load, low RPM, so if you want to maximize your efficiency while accelerating, you'll be better off with a higher gear at a higher load, than a lower gear at a lower load.
It was interesting to see 4th and 5th gear comparison while going up and down hill. 4th being slightly more efficient at some points.
It would also be interesting to do this same format in combination with your coasting video.
Maybe also an acceleration run with a block under the accelerator to hold it at a certain point while changing gear at different rpms?
Ok so this a great video. Although I must say, this is highway driving. To keep it simple as possible, if driving in a busy city drive as though you don’t have a brake (engine braking) and simply use the actual brake only when you really have to. Just by doing that your fuel economy changes to the better drastically.
I don't drive a car yet. But thanks for this.
Low speed, high gear... rather than high speed, low gear... got it.
👍😊
For all the non-turbo petrols I have driven, I find the 'sweet spot' is invariably 2000rpm.
Basically be gentle and ride the torque :)
But what if you drive a Honda? :)))
I had a 1987 gutless Toyota 22R, 4 cylinder pick up, about 100 ponies. Didn't matter when I shifted it never had good torque and never had good power, seriously, useless in passing.
Make sure your webcam is on before you ride the torque. Otherwise you won't make any money.
Correct me if I'm wrong, but don't you take the best of every fuel drop when the engine is working at it's higher torque zone? I mean, if you are in an uphill, won't you be taking better advantage of the fuel used with the engine working at it's optimum torque zone than with it working at low rpms meaning that it is not working at it's optimum point? Thanks!
The video shows where you get the most power per amount of fuel, which is the brake specific fuel consumption map shown. This doesn't necessarily correlate with peak torque.
Engineering Explained Is there any resources available to show the bsfc for a given engine or are there any correlations you can make from the more common dynograph?
the fuel entering the engine is burned almost 100% almost all the time. So per gram of fuel entering the engine the same amount of energy is being prodused. from that energy we end up using about 25% and the rest is being lost.
But when you operate your engine at low rpm you have less friction forces to evercome and less pumping losses becouse you have to open the throttle more to create enought power thus letting the air pass easier. so we end up useing 29% of the burned fuel for example.
to conclude its not that we take better advantage of the fuel but redusing the energy losses.
Νίκος Σεβασλίδης Thanks for the awesome explanation! That's what I was asking for. You explained it very well, thanks again!
As he said, depends on the car and engine. My car has peak torque at 2000 rpm and has a quite flat torque curve, so economic driving is easy for me.
If you want power higher go higher rpms, if you want fuel economy go lower rpms. This is pretty basic knowledge which we already know but glad someone is making money reiterating it.
Hi Jason, I've been trying all types of driving and shifting methods over the last 10 years with my 2009 Tacoma 4.0 litre and logging it. Not scientific, but over time I can see trends as well as tank specific mpg. After using this method, my last four city-only tanks of fuel have yielded 22.2 - 24.7 IMP mpg (Canadian here). Previously, I was getting 17 - 19.5 city-only IMP mpg. I previously was driving in 3rd-4th gear at 60kpm, shifting at 3000rpm and coasting at 2200 rpm and using a vacuum gauge to try and get the best mileage (as I was told that the highest vacuum numbers = best mpg). NOW, I'm shifting at 2000rpm and ending up in 5th at 60 kph with my rpm's at 1450. I'm assuming that "lugging the engine" would be any chattering or vibrating during acceleration in too high a gear? If I need to accelerate, I'll drop into 4th or 3rd. The vacuum gauge still gives high numbers, but drops more easily and quickly, with less pedal input in a higher gear as opposed to in a lower gear. Anyways, thanks for all the great content! I was posting more to confirm and illustrate to others the effectiveness of this method, rather than tell you something you already know and made a youtube video of... :) Ps, I'm lifted 3 inches and running 33's, so I'm really happy with the results, especially!!!