The Auto Union racing cars were high-tech products in their time. They stood for supreme achievements in motor-vehicle construction that concentrated above all on high-performance engines, aerodynamic design, and the systematic use of lightweight construction. The Auto Union car with streamlined fairing and an output of 545 horsepowerHorsepowerAlong with torque, horsepower is one of the key measures of engine performance. Horsepower was the first to exceed a speed of 400 km/h on a normal road.