On May 9, 1937, has of only 750 kilos heavy Mercedes car its race debut W 125 and prompt prevails. Then he will dominate the entire season in 1937. But only this one, already 1938 is the 750 kg formula story.
W 125 was established within a few months. The reason for the rush: The predecessor of W 25, the first of the legendary Mercedes silver arrows, is no longer competitive compared to the racecars of Auto Union. So the designers make in August 1936 at the factory. On 9 September, a first overall draft exists. Oval tubes as longitudinal beam and crossbar round tubes increases the rigidity and the suspension Gets a soft suspension as well as a strong damping. The aerodynamics of the body with the characteristic three cooling vents on the front is also optimized: the coefficient of drag is reduced from 0.62 to 0.59.
The development of the engine is evidence of particular courage from today's perspective. Because the last season will be the year of 1937, where the 750 kg formula applies 1938 introduces a displacement-related formula. Then, the unit has no chance to be used in the premier class of racing. But everyone involved, starting from the management, support the project. Thus arises the M 125, an eight-cylinder mechanically supercharged by a roots compressor 5.660 cubic centimeter engine capacity. On the test bench, the aggregate 646 makes HP. Thus, 125 speeds exceeding 300 km/h achieved the W.
The first of a total of eleven built W 125 will be ready in February 1937. Racing Debuts at the Grand Prix of Tripoli early may, where he is carrying the day. In the remainder of the season, Mercedes wins four of five big prizes, and Rudolf Caracciola is European Champion (for the second time after 1935). In addition, Caracciola 1938 achieved two speed records on the highway between Frankfurt am Main and Darmstadt. He enters a fully faired W 125 with a 736 PS strong 5.6-liter twelve-cylinder. Thus, he creates the kilometer with a flying start with 432,7 km/h and the mile with flying start with 432,4 km/h until today the highest speed achieved on a public road. (sl)