The BMW 3/15 hp DA 3 “Wartburg” quickly became a popular and successful sports car thanks to several engine changes. The 750 cc four-cylinder engine of the small, lightweight roadster was tuned from 15 to 18 hp using increased compression, a copper intake manifold and a dual exhaust system. They only had 400 kg to move. The Roadster was a milestone in BMW automotive sport history, with only 150 units built by 1931.