The 1921 Rumpler Tropfenwagen, or "drop car," was the world's first streamlined production vehicle, debuting at the Berlin Auto Show. Designed by Austrian aircraft engineer Edmund Rumpler, this rear-engine, five-seater had a remarkably low drag coefficient of 0.28, a value considered competitive even today. Innovations included the application of aircraft streamlining principles, curved windows, and swing axle rear suspension, enabling a top speed of 70 mph. Despite its advanced design, only about 100 units were built due to poor sales and reliability issues. Just two examples survive; it gained lasting fame from its appearance in the 1927 film Metropolis.