Mercedes 120 hp Grand Prix racing car, 1907

Mercedes 120 hp Grand Prix racing car, 1907

Given that the 1906 racing season had been disappointing overall for Daimler-Motoren-Gesellschaft (DMG) - not least due to internal disputes over the six-cylinder racing engine newly developed by Wilhelm Maybach - the Mercedes racing cars were in great need of technical modernisation - at least for participation in top-level sport. Following the ignominious discrediting of Wilhelm Maybach in his function as Technical Director and Chief Designer of DMG, it was now up to Paul Daimler to restore the competitiveness of the Mercedes racing cars for the 1907 season with a suitable design.

To this end, DMG again turned to a four-cylinder engine with a displacement of 14.4 litres and bore/stroke dimensions of 175 x 150 mm. In contrast to the engines of previous years, the design of the engine was largely modelled on the six-cylinder engine that Daimler had developed the previous year as a deliberate counterpoint to Wilhelm Maybach's ultra-modern unit. The uninspiring IOE valve arrangement, with its single side-mounted, gear-driven camshaft and the antiquated touch-spark ignition, thus made a comeback. Despite this design, which could hardly be described as representing the state of the art, Daimler succeeded in eliciting a maximum output of 120 hp/88 kW at 1400 rpm from the four-cylinder engine.

The four-cylinder engine was implanted in a heavily modified chassis, which essentially corresponded to that of Maybach's six-cylinder racing car. The pressed steel longitudinal members were offset at the front axle to allow a flatter vehicle silhouette, and the wheelbase was 2690 mm. A significant innovation was that the two rigid axles, which were fitted with semi-elliptic springs, now also had friction shock absorbers, which were designed to limit the inherent behaviour of the two wheel suspensions.

As with the six-cylinder racing car, the tank was no longer cylindrical in shape, but had a triangular cross-section. However, it was now mounted upright behind the seats, which made mounting and handling the spare wheels even easier. 

The new racing car made its racing debut at the French Grand Prix, which was held on 3 July 1907 on a triangular circuit near Dieppe in northern France. In contrast to the previous year, the entire race took place on just one day, during which the 76.988-kilometre circuit had to be completed ten times. With a series of difficult bends, the Grand Prix circuit was considered challenging, and the field of 38 cars on the grid consisted exclusively of domestic makes, apart from the three Mercedes and three FIATs.

At the end of the almost 770-kilometre ordeal for both man and machine, French star driver Victor Hémery only managed 10th place, an hour and three quarters behind the winner Felice Nazzaro, who had managed to keep the French phalanx at bay in his FIAT. Hémery's Mercedes team-mates Otto Salzer and Camille Jenatzy, along with 22 other drivers, had retired early - Jenatzy on the eighth lap and Salzer on the last.

While the performance in France was a disappointment compared to expectations, there were rays of hope three and a half weeks later at the Ardennes race. The event comprised a total of four races for different categories, including two over eight laps of 85.71 kilometres each: on 25 July 1907, the race for cars based on the Kaiserpreis formula, which proved very popular and attracted 23 participants, and two days later the race for cars based on the Grand Prix formula, in which only four other cars took part apart from the two Mercedes of Pierre de Caters and Camille Jenatzy. Baron de Caters won by one and a half minutes ahead of Guinness in a Darracq, and Jenatzy was third, 20 minutes behind.

The Grand Prix cars were equally successful at the Semmering race on 22 September, where Willy Pöge and Otto Salzer took first and second place in the 8-litre plus class. Pöge even managed a new Semmering record of 80.1 km/h.

Starting with the inaugural race on 6 July 1907, the Mercedes racing cars also put their capabilities to the test at the new Brooklands race track in Weybridge in the south of England until the end of the season in October. The Briton J. E. Hutton and his strongest rival, the Italian-born but British-raised Dario Resta, spurred each other on to new heights in their Mercedes racing cars and took a string of victories. However, they initially used the previous year's model before switching to the current Grand Prix car as the season progressed. In April 1908, Resta achieved 153.643 km/h over the half mile with a flying start in one of these cars and even set a new Brooklands record of 143.38 km/h over 44.5 kilometres.

By this time, the racing career of the first Mercedes Grand Prix car to be developed from scratch on the European mainland was already over: a change in the technical regulations for the 1908 Grand Prix de l'A.C.F. necessitated a fundamental redesign of the engines.

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