A prototype built to explore the higher speeds and lightweight aluminum body build processes in order to study efficiency, and tires. If I read the translation correctly, it was to research what could be done to drive from Berlin to Rome in 1938. Previous efforts at redesigning an existing chassis, or adding more powerful engines was found to not attain the goal, so the body was lightened, and streamlined to reduce parasitic drag loss.
At the same time, Dunlop was looking for a long distance high speed research car for evaluating it's Autobahn tires at 170 km/h
An American soldier had the car from some time during, until after the war, and painted it to match Army vehicles, then it was parted out or reverse engineered, and then the car finally made it to the Mercedes Museum in the 50s, well, the frame and rear axle did.
Fortunately the templates still existed, and in 2011 the car was recreated by Mercedes-Benz Classic experts