In 1938 a new racing formula was introduced, limiting the engine displacement of supercharged race cars to 3 liters. This rule change redefined the direction of motor sport racing for the succeeding years.
Mercedes-Benz developed an entirely new 485 hp V-12 engine for the W 154. A 5-speed transmission was added and mounted directly on the de Dion rear axle. One fuel tank was in the rear, and a second tank was in the cockpit, above the driver’s legs. In this car, the Daimler-Benz team of Caracciola, Lang, von Brauchitsch, and Seaman gained one victory after another. In 1938, Caracciola became European Champion. At the French Grand Prix on July 3, 1938, Mercedes-Benz earned a triple victory: von Brauchitsch came in first, Caracciola second, and Hermann Lang third. In 1939, Hermann Lang became European Champion with a revamped W 154.