In 1952, Uhlenhaut designed the Mercedes-Benz W194 "300SL" race car based on the Mercedes-Benz W186 limousine. The underpowered car achieved surprising success, winning important sports car races such as the 24 Hours of Le Mans, and inspired the road-going Mercedes-Benz W198 "300SL Gullwing" of 1954.
Based on the Mercedes-Benz 300 SLR sports cars racer of 1955, Uhlenhaut created a road legal race car with gull wings. Capable of 290 km/h, this [Uhlenhaut Coupé] was regarded as the world's fastest car in the 1950s, and it is rumoured that, running late for a meeting, Uhlenhaut exploited the unlimited-speed autobahns to make today's two-and-a-half-hour journey from Munich to Stuttgart in just over an hour..
Rudolf Uhlenhaut, who never possessed a car of his own, retired in 1972. He needed hearing aids, possibly due to hearing damage caused by his loud cars.