The AIACR (Association Internationale des Automobile Clubs Reconnus) in Paris announced a new formula for Grand Prix racing, formulated in 1932 and due to come into effect in 1934: the cars, without fuel, oil, coolant, and without tyres should weigh no more than 750 kilograms, but otherwise the engineers were not subject to any further restrictions. The Mercedes-Benz company decided to build a new racing car according to this formula. This decision promoted by MB racing manager Alfred Neubauer was finally reached at Mercedes-Benz in 1933. The new car designated the Mercedes W25 was produced under the technical direction of Dr. Hans Niebel with Max Wagner as head of chassis design, Albert Heess and Otto Schilling were in charge of engine development and Fritz Nallinger’s experimental department overseeing the building and testing of the actual race cars. Unlike Auto Union Mercedes-Benz adopt a conservative front-engined layout. The chassis was based on U-section pressed steel frame. Power was provided by a twin OHC supercharged straight eight 3.6-litre engine capable up to 494 horsepower. The suspension was all-independent with wishbones and coil springs at the front, swing axle and transverse quarter elliptics at the rear. In 1934, the first test drives with the prototype of new racing car painted in German racing white color took place from February onwards in Monza as well as on the motorway between Milan and Varese. With 320 hp (235 kW) – subsequently 354 hp/260 kW with a new blend of fuel – the car reached top speeds of more than 250 km/h. The car’s first appearance should have been at the Avus race in Berlin in May 1934, but participation was cancelled at the last minute due to technical problems. And so it was that the new car did not make its debut until a week later, on 3 June at the International Eifel race on the Nürburgring. The legend, supported officially by the Daimler-Benz, says that W25 went to the starting line in silver livery after the racing cars were stripped of their white paint at the Nürburgring to reduce weight. So the W25 is considered as the vehicle that gave rise to the name “Silver Arrow”. If the story of paint removal is true or not is not clear, but the first time when Mercedes-Benz car was nicknamed a “silver arrow” was in 1932 when Manfred von Brauchitsch raced a SSKL covered with streamline aluminium sheets, in Avus-Rennen. In 1934, the W25 won four major races (Eifelrennen, Coppa Acerbo, Spanish and Italian GP) compared to three for Auto Union (German, Swiss and Czech GP). In 1935, the European Championship was resumed, and it was won by Rudolf Caracciola in a W25. In modified form, the W25 remained in use until 1937, when it was succeeded by the Mercedes-Benz W125.