Mercedes 140 hp Grand Prix racing car, 1908

Mercedes 140 hp Grand Prix racing car, 1908

After the first two iterations of the Grand Prix organised by the French Automobile Club (A.C.F.), the cards were reshuffled for all those car manufacturers who wanted to take part in this now successfully established event going forward.

Inspired not least by the economic success of the previous year's race, the organisers of the A.C.F. decided to hold the Grand Prix on the circuit near the northern French town of Dieppe again in 1908 and also to redesign the technical regulations. A maximum bore of 155 mm and a minimum vehicle weight of 1100 kg were now stipulated. At the same time, the use of the innovative Rudge Whitworth wheel hub developed in England, which made it possible to remove a wheel as a whole from the vehicle, was banned - a clear advantage over the removable rim rings from Michelin, which were first used in 1906 and had given the domestic participants a clear competitive advantage.

The new regulations also meant that Daimler-Motoren-Gesellschaft (DMG) had to rethink the cylinder dimensions. Instead of tackling a completely new design, it was decided, also in view of the tight economic situation, to continue using Wilhelm Maybach's basic design of a four-cylinder with IOE valve arrangement realised in 1903.

In order to achieve an increase in performance compared to the only moderately successful Grand Prix racing car of the previous year, it was necessary to significantly lengthen the stroke of the four-cylinder engine in view of the maximum bore size of 155 mm imposed by the regulations. In order to have several alternatives, Paul Daimler commissioned the production of two engine variants with different stroke dimensions. One had 170 mm and a total displacement of 12.8 litres; the other 180 mm with a good 13.5 litres of displacement. While the smaller engine achieved a peak output of 130 hp/96 kW according to the entry in the order book, the larger engine delivered 138 hp/102 kW, both at a rated speed of 1400 rpm. In order to ensure adequate cooling for the increased horsepower output, a second fan was placed directly on the radiator in addition to the engine flywheel, which was designed as a fan.

However, Paul Daimler's attention was not only focussed on the four-cylinder racing engine. The chassis also had to be further developed if the company wanted to have a chance of winning against its numerous competitors. The low-built car, which like the previous year's model had a wheelbase of 2690 mm, had a very compact appearance and once again featured a newly designed fuel tank, which was located almost directly above the rear axle. The body, originally still in the classic form with open side sections, was visibly raised at the sides in the final phase of development to protect the car's occupants in the cockpit area.

Among the numerous modifications to the chassis, one stood out in particular: after the experience of the previous year, Mercedes had also switched to Michelin wheels, whose removable rim rings attached with bolts made the conventional tyre change superfluous and thus enormously shortened the pit stop times. In addition, different tyre dimensions were specified for the front and rear axles, which also took account of the different loads.

For the Grand Prix de l'A.C.F. scheduled for 7 July 1908, 48 participants had registered by the entry deadline. Eight domestic brands were pitted against three German brands, Mercedes, Benz and Opel, two Italian brands, FIAT and Itala, two British brands, Austin and Weigel, and one Belgian and one US brand, Germain and Thomas. With three vehicles per manufacturer, Germany had the largest foreign contingent. People on the Stuttgart side of the Rhine had also recognised how important the event had become - also in terms of advertising - and how important it was to face even the toughest competition.

In order to prepare optimally, the Mercedes team took advantage of the opportunity granted by the organisers to test the track in Dieppe with touring cars until 30 April. On race day, two veterans, Otto Salzer and Willy Pöge, lined up at the start, while talented newcomer Christian Lautenschlager - like Salzer, a foreman in the DMG driving department - completed the Cannstatt factory delegation. While the first two drivers competed in a 140 hp racing car equipped with a long-stroke engine, Lautenschlager drove the nominally somewhat less powerful car with a short-stroke engine. Starting at 6 a.m., the participants set off at one-minute intervals on the 76.989 kilometre course, which, as in the previous year, had to be circuited ten times.

The race was turbulent right from the start because, as in the two previous iterations of the Grand Prix, wheels and tyres played an important role in deciding victory or defeat in 1908 too. It also quickly became apparent that the Mercedes in particular had not only increased their speed, but were also demonstrating impressive reliability, while the vehicles from other manufacturers were increasingly struggling with technical problems. Nevertheless, it was truly a sensation when the young Christian Lautenschlager crossed the finish line as the winner after a race duration of 6 hours and 46 minutes and no fewer than 11 wheel changes. Following less than 10 minutes behind were two drivers from the Benz & Cie factory team, Victor Hémery and René Hanriot, in second and third place. Willy Pöge in the second Mercedes finished fifth; Otto Salzer had to retire after two laps with a defective wheel rim.

The result of the Grand Prix de l'A.C.F. was a nightmare for the French car manufacturers, who had become so used to success: only one of the seven first-placed cars bore one of their badges; the other six were from Germany. After a long dry spell, DMG in particular had benefited from the elaborate and meticulous preparation of the Mercedes racing cars and the high level of commitment of all those involved. The internationally acclaimed victory in Dieppe subsequently gave a considerable boost  to the Untertürkheim-based company's reputation, as it impressively demonstrated the performance and reliability of the Mercedes racing cars.

The article in the Vienna edition of the "Allgemeine Automobil-Zeitung" of 19 July, in which the trade magazine "Auto" is quoted, also bears witness to this: "Let us not forget that we are dealing with a first-class company whose workshops have often been the birthplace of automotive progress. Today we are allowed to say it: for a while, it seemed as if the heads of the Mercedes brand were somewhat neglecting the sporting manifestations. More than once, the brand sent cars into the race that were not sufficiently au point and were ready to race far too late; the race organisation also often seemed a little haphazard. There was no sign of any of this today. [...] This whole little world, drivers and mechanics alike, showed such discipline and such combativeness and such eagerness to win that I realised how right Théry was when he told me that day: the one I'm most afraid of is Mercedes."

The Mercedes Grand Prix racing car achieved further successes at the Ostend Week in July, at the Brooklands circuit in the south of England in August and October and at the Semmering Race in September 1908. In addition to the version used in the Grand Prix, variants with larger-displacement and more powerful engines were also used in these competitions. At the Semmering race, Otto Salzer and Willy Pöge took first and second place in the Grand Prix car category and also achieved the same result in the class for racing cars with no limit on bore and weight. With a race car without a limit, Salzer also set the best time of the day with 7 minutes and 23.6 seconds to set a new track record. His racing car, like the one driven by Pöge, had a larger 15.4-litre engine with a 175 mm bore and 160 mm stroke.