The Auto Union Grand Prix Racing Cars types A to D were developed and built by a specialist racing department of Auto Union’s Horch works in Zwickau, Germany, between 1933 and 1939, after the company bought a design by Dr. Ferdinand Porsche in 1933.
Of the 4 Auto Union racing cars, the Types A, B and C, used supercharged V16 engines from 1934 to 1937, and the Type D, built in 1938 and 39 to new regulations, had a supercharged 3L V12 that developed almost 550 horsepower. All of the designs were difficult to handle due to extreme power/weight ratios (wheel spin could be induced at over 100 mph (160 km/h)), and marked oversteer due to uneven weight distribution (all models were tail heavy). The Type D was easier to drive because of its smaller, lower mass engine that was better positioned toward the vehicle’s center of mass.
In 1932 Auto Union GMBH was formed, comprising struggling auto manufacturers Audi, DKW, Horch and Wanderer. The chairman of the board of Directors, Baron Klaus von Oertzen wanted a show peace project, so at fellow director Adolf Rosenberger’s insistence, von Oertzen met with Porsche, who had done work for him before.
Between 1935 and 1937, Auto Unions won 25 races, driven by Ernst von Delius, Tazio Nuvolari, Bernd Rosemeyer, Hans Stuck,, and Archille Varzi. 1938 brought new challenges, principally the death of Rosemeyer early in the year, in an attempt on the land speed record. The famed Tazio Nuvolari joined the team, and won the Italian and Donington Grands Prix, in what was a thin year for the team, other than yet another European Mountain Championship for Stuck.
In 1939, as war clouds gathered over Europe, Nuvolari won the Yugoslavia Grand Prix in Belgrade (with a second place in the Eifel). Hermann P. Müller won the 1939 French Grand Prix (and took second in the German Grand Prix). Hasse managed a second place in the 1939 Belgian Grand Prix, and George Meier a second in the French.
Presently it is believed that only one Type C and three Type D cars, and a Type C/D hill climbing car remain.