That's why this old Porsche looks so strange.

That's why this old Porsche looks so strange.
The unique contraption was wrapped in absorbent cotton at one point.
Porsche 928 noise test car.
It's difficult to build a car that must comply with increasingly stringent laws. Not only do automakers have to consider emissions and safety regulations, but also specific criteria regarding noise levels. Ensuring that cars are not too loud is particularly difficult for companies specializing in high-performance vehicles. They tend to have louder exhausts as well as wider tires, which tend to be noisier.
In the late 1980s, Porsche had to build this contraption to make sure its sports cars wouldn't be too loud. Based on the 928, this unique prototype started in 1989, just as Back to the Future 2 hit the big screen. In an alternate universe, Dr. Emmett "Doc" Brown would drive it instead of the DeLorean DMC-12. We think the strange car from Zuffenhausen would also fit perfectly into a dystopian action movie like Mad Max.
While Doc's time machine used a stainless steel body like the Cybertruck , Porsche wrapped the car's body with absorbent cotton. This helped engineers isolate and minimize the sources of engine, intake and exhaust noise. The idea behind this 928 was to evaluate the noise levels of different tire compounds. That's why some of the car's innards were moved outside the body.
Indeed, the radiator was placed in front of the front bumper, and those two clunky hoods housed a pair of fans to cool the engine. The large barrel stuck to the hood is where the intake process took place, with cables connected to the perfectly enclosed engine bay. Let's just say outside visibility wasn't a priority.
The view through the rear window was even worse, as the custom exhaust system had a huge muffler attached to the glass. The twin curved exhaust pipes were hand-welded and brought out to the highest point of the car, facing the rear. As for the bulging wheel arches, they were added to allow the 928 to accommodate different types of wheel and tire combinations. In its current form, low-profile rubber encircles the alloy wheel from the previous generation 911 .
But why did Porsche initially choose the 928? Because the air-cooled 911 was simply too loud for the job. The 924 was also ruled out because the engineers wanted a car with lots of power in the lower rev range. The 944 was also unsuitable for the job because of "gearbox rumble at low loads," according to Porsche mechanic Harald Mann. He's been with the company for 40 years, most of which he's spent on test stands to assess noise levels.
Porsche originally tested the car on an existing test stand, but its coverage changed over time and the company had to improvise. "The Exterior Noise Measurement Track" was built using standardized asphalt to eliminate variables and get more accurate results. The 928 was fitted with smooth tires, and its noise level was measured at a low 63 dB during a standardized span test at 31 miles per hour. When the test was conducted, the acceptable limit was much higher at 74 dB.
This 928 may be an ugly duckling, but it perfectly illustrates the "form follows function" principle. The rolling test stand helped Porsche make its cars quieter, which may seem counterintuitive, but it was necessary to meet noise regulations. After more than three decades of service, it now rests in the Porsche Museum in Stuttgart.