The elimination of a driveshaft saved weight, and the rear-mounted engine was a large, lowly stressed, light alloy design. Rather than the then-popular inline eight layout, they used a 4.36 litre, 45-degree, supercharged V16 developing 295 horsepower.
More weight was saved by such ingenious methods as having one camshaft operate all 32 valves, and casting the intake manifolds as part of the cylinder heads.
Over the years, the displacement of the P-Wagen (for Porsche) would climb to 6.0 litres and 500-plus horsepower. Mercedes-Benz used a 3.36 litre, 354 horsepower inline eight for 1934, and it too would gradually grow in size and power.
The Auto Union proved to be a handful to drive, due in part to the swing axles. Although the small, light, low powered Volkswagen could get away with this layout, it would prove to be a handling challenge in larger, more powerful cars, as Chevrolet would learn 30 years later with the rear-engined Corvair.
Although not posting as many victories as rival Mercedes Benz, Auto Union was still quite successful, especially when piloted by the courageous and highly skilled Bernd Rosemeyer. AU won three GP races in ’34, four in ’35, six in ’36, and five in ’37. Ten of these 18 victories were by Rosemeyer.
Ferdinand Porsche would part with Auto Union in 1938. With him would go the swing axles, replaced by a solid de Dion type. And the V16 engine was replaced by a V12.
Auto Union would win only three more GP races before racing ended with the outbreak of the Second World War in 1939. Two of the wins were by the great Italian ace Tazio Nuvolari, recruited to replace Rosemeyer who was killed in 1938 in an Auto Union while attempting a land speed record on an autobahn.
Auto Union and Mercedes-Benz race cars dominated the Grand Prix circuits during the last half of the ’30s. They achieved Hitler’s purpose of demonstrating Germany’s technological might. By 1939 Germany’s attention was being consumed by more sinister motives, where much of the race-generated technology would be exploited.
Despite Auto Union’s success, the rear engine layout was never fully accepted for racing cars during the 1930s. It was regarded as a temporary aberration.
Some 30 years would pass before Porsche’s P-Wagen foresight was vindicated, and mounting the engine between the driver and the rear axle would dominate top-echelon racing. Unfortunately Dr. Porsche would not live to see it; he died in 1951 at age 75.