Rumpler Tropfenwagen
The Rumpler Tropfenwagen ("Rumpler drop car", named after its raindrop shape) was a car developed by Austrian engineer Edmund Rumpler. The Tropfenwagen. Aerodynamics. Rumpler, born in Vienna, was known as a designer of aircraft when at the 1921 Berlin car show he introduced the Tropfenwagen. It was to be the first "streamlined" production car, before the Chrysler Airflow and Tatra T77. The Rumpler had a drag coefficient of only 0.28, a measurement which astonished later engineers and would be competitive even today. For comparison: the top ten most aerodynamic production cars in 2014/2015 were in the range 0.26  down to 0.19. The Fiat "Balilla" of the mid-1930s, by contrast, was rated at 0.60. To enable the car's aerodynamic shape, the Tropfenwagen also featured the world's first (single plane) curved windows. Both the windscreen and the side windows were significantly curved. Engine. The car featured a Siemens and Halske-built overhead valve W6 engine, with three banks of paired cylinders, all working on a common crankshaft. Producing , it was mounted just ahead of the rear axle. The engine, transmission, and final drive were assembled together and installed as a unit. The Rumpler-invented rear swing axles were  suspended by trailing leaf springs, while the front beam axle was suspended by leading leaf springs. Seating. Able to seat four or five, all the passengers were carried between the axles for maximum comfort, while the driver was alone at the front, to maximize view. With the 1923 model, two tip-up seats were added. Performance, models, influence. Weighing , the "Tropfenwagen" was nevertheless capable of on its mere . This performance got the attention of Benz & Cie.'s chief engineer, Hans Nibel. Nibel conceived the Mercedes-Benz "Tropfenwagen" racers using the virtually unchanged Rumpler chassis. Poor sales and increasing losses led  Benz to abandon the project. Later Auto Union racing cars resembled the Benz Tropfenwagen racers and were built in part by Rumpler engineers. Rumpler made another attempt in 1924, the 4A106, which used a inline 4-cylinder engine. This compelled a growth in wheelbase, with a consequent increase in seating to six or seven. Sales. Although the car was very advanced for its time, it sold poorly – about 100 cars were built. Sales were hindered by small problems at the start (cooling, steering), the appearance of the vehicle, and the absence of a luggage compartment. Most were sold as taxis , where easy boarding and the high ceiling were advantages. The last cars were built in 1925. In "Metropolis". The "Tropfenwagen" did become famous thanks to the film "Metropolis", in which Rumplers found a burning end. It also inspired the Mercedes-Benz 130H / 150H / 170H road cars. Surviving specimen. Only two examples are known to survive, one in the MVG public transportation museum in Munich, and one in the German Museum of Technology in Berlin.