Mercedes 90 hp racing car, 1903

The Mercedes-Simplex 90 hp was created in 1903 as a pure-bred racing car in parallel with the Mercedes-Simplex 60 hp touring and sports car. This marked the first step towards specialisation at Daimler-Motoren-Gesellschaft (DMG), which increasingly differentiated the racing cars used in top international motorsport from regular production vehicles. The underlying technical design of the two four-cylinder engines used in these vehicles, developed by Josef Brauner, was identical. One innovation was the so-called IOE valve arrangement (for intake over exhaust), whereby the intake valves were suspended above the upright exhaust valves. The overhead intake valves were actuated by tappets and rocker arms, while the exhaust valves, which were arranged in a separate chamber on the side of the cylinder, were moved directly by the gear-driven camshaft below.

The disadvantage of the unfavourably shaped combustion chamber with poor efficiency, which was of little consequence at the time due to the low speed and compression level, was easily compensated for by the ease with which the IOE configuration could be repaired. In the early days of engine design, it was difficult to control the combustion process with regard to possible heat pockets with the existing level of knowledge, materials and instruments. Engine damage caused by burnt exhaust valves was a common problem.

However, a distinctive and unusual characteristic of the racing engine for the era was its decidedly oversquare, i.e. short-stroke, design. The dimensions for bore and stroke were 170 x 140 mm, resulting in a total displacement of 12,711 cc. However, the reason for these cylinder dimensions was not to lower the piston speeds or to increase the engine speed, but simply to keep the height of the engine, which was prominently positioned in the airstream, as low as possible in the interests of better aerodynamics. The Mercedes-Simplex 90 hp "Special racing car", which DMG initially officially designated as 80 hp or 80/90 hp, had an output of 83.8 hp/61.6 kW at 1050 rpm according to the surviving original records. The other technical specifications of the Mercedes 90 hp racing car were essentially based on the standard of the Mercedes Simplex 40 hp from the previous year. The stable backbone was still a cross-braced frame made of pressed steel side members with a U-profile, two rigid axles with semi-elliptical springs took care of the wheel guidance, water-cooled brakes on the rear wheels, the transmission output shaft and the intermediate shaft to the chain drive took care of the deceleration. To further improve driving stability, the wheelbase of the car was extended by 240 mm to 2690 mm compared to the 40 hp model. With a vehicle weight of 1000 kg, which was limited by the regulations of the Gordon Bennett race, the result was a very respectable power-to-weight ratio of 11.9 kg/hp.

However, the motorsport career of DMG's first 90 hp racing car was short-lived and rather unfortunate. Following the delivery of the first car on 18 April 1903, the test phase had to be shorter than usual in order to ensure participation in the Paris - Madrid long-distance race at the end of May 1903. 

The event, which generated considerable interest and was eagerly awaited by the general public, was organised in three stages over a total of 1307 km, but was unable to meet these high expectations and ended in nothing short of disaster. Out of 315 registered vehicles, a total of 224 appeared at the start in Versailles, including 88 cars in the heavy class from 650 to 1000 kg and 54 motorbikes. The first participants were set on their way on 24 May at 3:45 a.m.; the last one finally started three hours later at 6:45 a.m., by when the first had already covered a good 200 km. Tens of thousands of spectators lined the streets. Visibility was extremely poor due to the dust stirred up by the numerous vehicles, and spectators kept crowding onto the track. This resulted in numerous accidents in which seven people - the drivers Marcel Renault and Claude Loraine-Barrow, three mechanics and two spectators - were killed and many others were injured, some of them seriously.

As a result, the race was stopped by the French authorities in Bordeaux, at the end of the 552 km-long first stage. This went so far as to ban the drivers from moving their vehicles even one metre further. The journey back to Paris had to be made by train, and cars were not even allowed to make the journey to the station under their own power. For DMG, the race was deemed to have been a failure. In addition to six brand-new 90 hp racing cars, five 60 hp and one 40 hp car were also on the grid. The best-placed Mercedes in the end was a 60 hp car, in which John B. Warden achieved fourth place in the heavy car class. The fastest 90 hp, driven by Camille Jenatzy, finished in 11th place. The other four cars that crossed the finish line were all behind the 60 hp and even behind the 40 hp, which finished in 12th place with Max at the wheel. The disastrous outcome of the event made the mediocre performance of the Mercedes-Simplex 90 hp fade into the background a little, but nevertheless showed that there was a need for action.

This was also stated in the report in the "Allgemeine Automobil-Zeitung" of 31 May 1903: "The Mercedes were disappointing. It seems to be the brand's fate to lose out in the main event of the year after triumphing in the spring. Until now, this has been understandable, as the Mercedes cars launched early in the year provided the French manufacturers with a welcome guideline as to how powerful they needed to make their racing cars for the forthcoming season. That was not the case this time, because the 60 hp Mercedes were there for the first races of the season, and the 90 hp Special cars for the big events. The former had delivered what was expected of them, but not the latter. A 60 hp Mercedes belonging to Mr. Warden has beaten all 90 hp Mercedes, and even the 40 hp Mercedes driven by Max was faster than the 90 hp of de Caters, Hieronimus and Werner. The performance of the 40 hp car should actually be the pride of the Daimler factories. But where were their 90 hp cars? They failed. It is said that the cooling-water tanks were too small to cool the machine sufficiently. This is quite possible, because the beehive of the 90 hp is smaller than that of the 60 hp. Why? The weight had to be less than 1000 kg, and since there was not a single gram to be saved anywhere, the radiator was reduced - as experience has taught us, this was an ill-advised economy. Nor was it particularly helpful that the cars went into the race almost directly from the factory." 

The Paris - Madrid city race, which had ended in tragedy and was abandoned prematurely, had also been planned by DMG as a dress rehearsal for the Coupe Internationale race, better known as the Gordon Bennett race, which took place seven weeks later in Ireland. This competition between national automobile clubs, which was initiated by James Gordon Bennett Jr., an American newspaper publisher, sportsman and automobile enthusiast living in Europe, was organised by the British Automobile Club in Ireland in 1903 following the previous year's victory by Selwyn Francis Edge of Great Britain and enjoyed broad international participation for the first time. This made it probably the most prestigious event of the still young automobile sport scene at the time.

In essence, this situation provided the best conditions for DMG to make up for the failure in the Paris - Madrid race and to demonstrate the competitiveness of the Mercedes-Simplex 90 hp. But things were to turn out differently: not even two weeks after the Paris-Madrid race, in the early hours of 10th June, a devastating fire destroyed the Cannstatt plant of Daimler-Motoren-Gesellschaft down to its foundations. In the process, 30 semi-finished and 70 almost finished cars, including the 90 hp racing cars, were destroyed in the flames. In order still to be able to take part in the Gordon Bennett race, Daimler-Motoren-Gesellschaft (DMG) asked some of its customers to loan back the 60 hp cars that had already been delivered to them.

Following the good performance of the Mercedes-Simplex 60 hp in the Paris - Madrid race, Max von Duttenhofer, Chairman of the DMG Supervisory Board, had already argued before the fire in Cannstatt in favour of replacing one of the vehicles for the Gordon Bennett race with a Mercedes-Simplex 60 hp instead of deploying three 90 hp cars. The vehicle of the American millionaire and automobile enthusiast Clarence Gray Dinsmore was intended for this purpose. However, after Dinsmore's 90 hp car had been destroyed in the fire and the millionaire did not want to do without a car, it took all the persuasive power of DMG sales director Robert Katzenstein to motivate Dinsmore to nevertheless make his 60 hp available. In the end, this was only possible because Katzenstein provided his own 40 hp car in exchange. The fact that the Belgian Camille Jenatzy actually took victory in Ireland in the 60 hp Dinsmore car was a sensation in view of the difficult starting position, which in the end consoled DMG for the unfortunate fate of its 90 hp racing cars.

For the following year, DMG then developed a version of its 90 hp racing car that had been improved in certain respects.