In 1960, Mercedes-Benz designed and built a one-of-a-kind mobile test lab called Messwagen, a German term that loosely translates to “measuring car.”

The Messwagen was essentially a 300 that was converted from a sedan to a station wagon in order to carry bulky equipment that recorded information such as how much horsepower an engine was generating, how much fuel it was using, and how hot it was getting. The rear bench was tossed out in order to make room for the equipment, but Mercedes installed a pair of wicker chairs so that engineers could monitor the testing process in real time.

From what we gather, the process began by hooking up sensors to the car being tested. Wires taped together ran out of the test car through a window that was cracked open, they were secured to a purpose-designed roof rack, and they ran into the Messwagen through a hood scoop located right above the front seats. That means the driver had to keep the 300 within a few feet of the test car, a process that we imagine was easier said than done.

The Messwagen was powered by a 3.0-liter straight-six engine tuned to generate about 160 horsepower at 5,300 rpm. The car being “tested” in the pictures below is an automatic 220S, which uses a 2.2-liter straight-six that makes 110 horsepower at 5,000 rpm. Both cars have a top speed of 103 mph (165 km/h).