Mercedes-Simplex 60 hp "Gordon Bennett" racing car, 1903
In parallel to the Mercedes-Simplex 90 hp, which was designed as a thoroughbred racing car, another high-performance car was developed for the 1903 model year, the Mercedes-Simplex 60 hp. This was also conceived for use in motorsport and in this function can be regarded as the actual successor to the 40 hp model from 1902. Like the latter, it was less uncompromisingly tailored to racing and its underlying character was closer to that of a particularly powerful sports car.
DMG engine designer Josef Brauner came up with a new four-cylinder engine, which was used in different versions in both the 60 and 90 hp cars. The engine intended for the 60 hp model had a displacement of 9.2 litres, was designed with a moderately long stroke with bore/stroke dimensions of 140 x 150 mm and delivered a maximum output of 65 hp/48 kW at 1060 rpm.
An innovation and special technical feature of both engines was the so-called IOE valve arrangement (for "intake over exhaust"), in which 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 opened and closed 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 development, 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. The IOE valve arrangement offered the advantage of making quick repairs possible, especially in competition situations.
The other technical specifications of the Mercedes-Simplex 60 hp were essentially based on the standard of the 40 hp model. The stable backbone was still a cross-braced frame made of pressed steel longitudinal members with a U-profile; two rigid axles with semi-elliptical springs took care of the wheel guidance, while water-cooled brakes on the rear wheels, the transmission output shaft and the intermediate shafts to the chain drive took care of the deceleration. To improve driving stability in the long term, the wheelbase of the 60 hp vehicle was extended by an impressive 300 mm to 2750 mm compared to the 40 hp model.
With the Mercedes-Simplex 60 hp, Wilhelm Maybach and Josef Brauner had created a vehicle that was as fast as it was reliable and demonstrated a wide range of qualities. Its motorsport debut at the Nice Race Week in April 1903 was marked by success, but also by a tragic accident. In the Nice - La Turbie hill climb on 1 April, Eliot Zborowski suffered a fatal accident in the new 60 hp when he lost control of his car at the start of the race and collided with a rock face at full speed - tragically in almost the same place where Wilhelm Bauer had had a fatal accident three years previously. Apparently Zborowski's cufflink had become caught on the accelerator lever on the steering wheel. Before this tragic accident, Otto Hieronimus, Wilhelm Werner and Henri Degrais had also completed the hill climb in Mercedes-Simplex 60 hp vehicles, with Hieronimus setting a new track record of 64.4 km/h. As a result of the accident, the prefect of the local 'Département' initially banned all further races in Nice Race Week, but eventually allowed mile and kilometre races as well as record attempts on the Promenade des Anglais on 7 April.
Hermann Braun achieved a top speed of 116.9 km/h in the 60 hp racing car, setting a new record for vehicles with a combustion engine. Behind Braun, a further five Mercedes Simplex 60 hp cars took second to sixth places. Only Léon Serpollet, who won the Coupe Rothschild for the third time in his streamlined steam car Le Turpilleur ("torpedo boat") with 123.300 km/h over the flying kilometre, and Hubert Le Blon, also in a Serpollet steam car, were faster than Braun. In the Paris - Madrid race, which was unusual in many respects and was stopped by the French authorities after just 552 kilometres in Bordeaux due to a series of fatal accidents, the 60 hp racing cars also performed very well and in some cases even outclassed the 90 hp cars that were being used for the first time.
However, the Mercedes-Simplex 60 hp went on to become a legend in July 1903 in the Coupe International race, commonly known as the Gordon Bennett race. The most prestigious event of the still young automobile sport scene at the time, which had been established by James Gordon Bennett Jr., an American newspaper publisher, sportsman and automobile enthusiast living in Europe, was held in Ireland in 1903 after the previous year's victory by the British driver Selwyn Francis Edge and enjoyed broad international participation for the first time. The start of the 60 hp cars was only an stopgap solution, as the Mercedes-Simplex 90 hp racing cars originally intended for participation had been destroyed by a devastating fire at the Cannstatt factory in the early hours of 10 June 1903, just three weeks before the race. Daimler-Motoren-Gesellschaft (DMG) had hurriedly requested back some of the 60 hp models that had already been delivered to customers and prepared them for the race over almost 600 kilometres.
After the good performance of the 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 with a Mercedes-Simplex 60 hp instead of deploying three 90 hp cars for the Gordon Bennett race. The vehicle of US 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 have to make do without a car, it took all the persuasive power of Frankfurt banker and later 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, who was nicknamed the "red devil" because of his red beard and fast driving style, actually took victory in the Dinsmore car was a sensation in view of the difficult starting point. The other two 60 hp cars were driven by Baron Pierre de Caters and Foxhall Keene, but neither driver was anything like as successful as the "red devil". In the end, the combination of Camille Jenatzy and the Mercedes-Simplex 60 hp brought DMG and the still young Mercedes brand their first major international race victory. The success of Jenatzy, who had been entered by the Imperial Automobile Club and had contested the race for Germany, meant that the 1904 Gordon Bennett Race was held in Germany for regulatory reasons. The winning car continued to be active in motorsport after being returned to Dinsmore: with Wilhelm Werner at the wheel, it took second place overall in the Semmering race, which was held for the fifth time, with a time of 9 minutes and 4.2 seconds or 66.2 km/h. However, Dinsmore had also entered a second 60 hp car, which started with Hermann Braun at the wheel. Braun set a new course record of 8 minutes and 47.6 seconds or 68.2 km/h and won the overall classification. Dinsmore was thus able to defend the trophy he had won the previous year for the best time across all categories.
The "Allgemeine Automobil-Zeitung" newspaper published on 27 September 1903 commented on this achievement as follows: "The Mercedes cars proved that they are top class in the most important race of the year when Jenatzy won the Gordon Bennett race for Germany in a Mercedes car, the same car that finished second in the Semmering race. And without wishing to offend the drivers in the Semmering race, we have to say that Braun and Werner are in a class of their own as drivers in terms of courage, cold-bloodedness, racing tactics and handling of the car. Only Hieronimus deserves a place alongside them. So the crack performers of the Mercedes stable move into their winter quarters crowned with new laurels." Even though the 60 hp car was on a par with its bigger brother in some respects, its motorsport career was short-lived. By 1904, a further developed 90 hp model was available, and by 1905 the performance level of the Mercedes racing cars had already reached 120 hp.