Mercedes-Benz W 196 R, 1955

For the 1955 season, the racing department in Untertürkheim had comprehensively revised the W 196 R, with the development focussing on increasing performance on the one hand and reducing weight on the other. Both served to ensure the competitiveness of the Formula 1 Silver Arrow in its second season. The key measure of the performance overhaul that was applied to the engine was the use of a straight intake manifold instead of the previously used curved variant. As a result, output was increased by almost 13% from 257 hp/189 kW to 290 hp/213 kW at 8500 rpm.

The straight intake manifold required more installation space at the top compared to the curved version from the previous year: As a result, the front end of the W 196 R was no longer symmetrical, but featured a prominent bulge for the intake manifold on the right-hand side, which dominated the front view. The intake of combustion air was thus separated from the cooling air inlet and took place via a mesh at the front of this bulge. The large cooling air intake at the front of the car was also given a framed wire mesh. It was designed to prevent leaves and shreds of paper from being sucked in and could be opened by the driver using a pull lever, whereby the accumulated objects were blown away by the airflow. This change was intended to effectively prevent thermal problems caused by a blocked cooling air intake, as had occurred in the previous year's Spanish Grand Prix.

The 1955 version of the W 196 R also experimented with different wheelbases, which were expected to save weight on the one hand and improve handling on the other. In addition to the standard frame with a wheelbase of 2350 mm, which had already been used in 1954, two shortened versions with 2210 mm and 2150 mm were available, all of which were also tested in racing. In the version with the short wheelbase of 2150 mm, which was realised in three vehicles, the inboard brake drums had to be moved to the outside of the wheels for reasons of space; in addition, there were two different installation positions for the engine in this variant. Due to the shortening of the wheelbase, the engine had been moved 60 mm further forward in relation to the centre of the front axle, but in one of the vehicles the engine had been moved forward by a further 60 mm.

The first race on the World Championship calendar, the Argentine Grand Prix, took place in mid-January 1955. It went down in history as the "heat battle of Buenos Aires". Fangio was one of the few drivers to finish the three-hour race alone without being relieved. Fangio won the race in a classic monoposto with open wheels in the medium wheelbase version, which was used here for the first time. 14 days later, another race took place in Argentina: the Grand Prix of Buenos Aires, which was organised without a formula. The Mercedes-Benz team was well prepared and, in addition to a 2.5-litre Formula 1 racing car driven by Hans Herrmann, also fielded three W 196 Rs equipped with the 3-litre engine from the 300 SLR racing car. Fangio also won this race, while Stirling Moss – the British newcomer to the Mercedes-Benz team – and Karl Kling finished second and fourth, respectively.

The short-wheelbase version took to the starting line for the first time on 22 May in the first race of the season in Europe – the European Grand Prix in Monaco. Fangio and Moss opted for this variant, while Hans Herrmann and the Frenchman André Simon, who was engaged for several races, chose a car with a medium wheelbase. This time, luck was not in favour of the team from Untertürkheim: Hans Herrmann suffered a serious accident during practice, and the other three cars failed with minor but serious defects.

Then the tide turned: The four remaining races of the Formula 1 season – the Belgian, Dutch, British and Italian Grand Prix – all ended with one-two victories for Mercedes-Benz, with Fangio usually finishing the race ahead of Moss. In the British Grand Prix, the Silver Arrows even scored a quadruple victory, led this time by Stirling Moss with Fangio, Kling and Piero Taruffi in 2nd to 4th place. In the Dutch Grand Prix, Fangio drove the short-wheelbase version to victory for the first time.

At the end of the season, Fangio was world champion – for the second time in a Mercedes-Benz and for the third time in his career. Mercedes-Benz succeeded in building on the successes of the pre-war period and won the world championship twice with a completely redesigned racing car. However, there was not to be a third season for the successful W 196 R. In the spring of 1955, the Board of Management had already decided to discontinue its Formula 1 involvement after the end of the season and to concentrate on sports car racing in future. In October 1955, at the height of its success, the unexpected decision was made also to refrain from participating in the World Sports Car Championship in 1956.