Mercedes 120 hp Grand Prix racing car, 1906

After the unsatisfactory course of the 1905 season, DMG urgently needed to take action in order to get back on track in 1906 and build on the successes of previous years. Wilhelm Maybach opted for a fundamentally new design with an extremely modern engine and chassis. However, the new racing car, in particular the six-cylinder engine with overhead camshaft and high-voltage magneto ignition envisaged by Maybach, led to serious differences between the "King of Designers" and his colleagues on the board, which delayed development, and so the four-cylinder car had to be used once again for the 1906 season.

The previous year's car was modified in certain respects: the chassis was given a wheelbase that had been extended to 2920 mm and a tank that was positioned slightly further forward. Some sources also mention a modification of the engine with a 4 mm longer stroke and the correspondingly slightly larger displacement of 14,432 cc, but this is not conclusively proven by primary sources.

Following disputes over the Gordon Bennett race and its limitation by the regulations to three participants per nation, the Automobile Club de France (ACF) reached a compromise at the beginning of 1905 - after difficult consultations with the French automobile manufacturers and the recently founded International Association of Recognised Automobile Clubs AIACR (Association Internationale des Automobile Clubs Reconnus) - that would allow them to organise the Grand Prix de l'Automobile Club de France from 1906 as a replacement for the Coupe Internationale and, in the event of a French victory in the 1905 Gordon Bennett race, as then actually occurred, not to organise a race for this competition in 1906. The first Grand Prix de l' A.C.F. took place on 26 and 27 June 1906 on the Circuit de la Sarthe not far from Le Mans. The 103.18-kilometre triangular course had to be circuited six times on each day, corresponding to a total distance of 1238 kilometres. There were 32 racing cars from 12 manufacturers on the grid, including three Mercedes 125 hp cars driven by Camille Jenatzy, the Italian Vincenzo Florio and the Frenchman Mariaux. After two gruelling days and a total driving time of 12 hours and 14 minutes, Ferenc Szisz won in a Renault; apart from him, only 10 other cars reached the finish line, including the two Mercedes of Alexander Burton and Mariaux. They were the last to come in, however, more than four hours behind the winner. The third Mercedes with Vincenzo Florio had already had to retire on the last lap of the first day after a tyre failure with a rim defect. Burton had replaced Jenatzy at the start of the second day after the latter had had to abandon the race at the end of the first day with badly inflamed eyes. The protective goggles were unable to keep out the fine abrasion particles from the tarmac track, and Jenatzy was so badly affected that he had to undergo eye surgery.

The major time delay with which the two Mercedes crossed the finish line was mainly due to tyre defects. This was also the view of the trade press; the "Allgemeine Automobil-Zeitung" quoted the Paris "New York Herald" in its issue of 8 July 1906: "The two Mercedes that remained for the second day were hopelessly beaten due to tyre damage. Time and time again, Mariaux and Mr Burton (who had stepped in for Jenatzy) were without a tyre on the right rear wheel and they had to drive for miles on the rims. The machines themselves ran well. Mariaux, whom I saw this evening, told me that not the slightest thing had happened to his engine during the whole 1200 kilometres, and Jenatzy, whose eyes were terribly damaged by the dust, told me the same. [...] The removable rim used by the winner Szisz was the main factor contributing to the victory of the Renault car. Szisz changed the pneumatic tyres no fewer than nineteen times during the entire 1200 kilometres, but with the help of the removable rim, barely five minutes were lost each time. There is no doubt that all the machines that completed the race and were officially classified are equally good. If they had all had invulnerable tyres, they might all have reached their destination within very short intervals of each other."

For DMG, this assessment was certainly little consolation. At the Ardennes race, which was held for the fifth time on 13 August - seven weeks after the Grand Prix - on the circuit near Bastogne, the Mercedes 125 hp of Otto Salzer, Camille Jenatzy and Alexander Burton were unable to achieve a better result, even though they were equipped with removable rims this time. Burton had stepped in again - this time for Mariaux, who had been ill at the start - but dropped out in the second of 7 laps. Of the 19 cars that started, 12 reached the finish line; the winner was Duray in a de Dietrich, while Salzer and Jenatzy had to make do with places 9 and 10. In its issue of 26 August 1906, the "Allgemeine Automobil-Zeitung" quoted the French "Les Sports": "[...] We can therefore not spare Mercedes, who build such wonderful touring vehicles, the reproach that their racing cars, on which the eyes of the whole world rest [...] are not on the same level as the touring vehicles. Mercedes was there only with the old racing cars from 1905 and, bearing that in mind, they did quite well. Salzer, a newcomer to the race, was even in second place for a long time. [...] The Cannstatt company owes itself another win, and it will get there."

For Otto Salzer - an employee in the DMG running-in department who was competing in his first race - the result was a great success, especially as he finished 19 seconds ahead of Jenatzy, but DMG could hardly be satisfied with a gap of 38 minutes to the winner. The "Allgemeine Automobil-Zeitung" had already got to the heart of the matter in its Vienna edition on 19 August 1906 and rubbed salt into the wound: "As in all the big races in which they have competed recently, the Mercedes had no luck this time either. [...] As in the Grand Prix, the Mercedes drivers started with the old racing cars from the previous year." It was clear that DMG was going to have to make considerable efforts to get back on a successful track.

There was at least one small ray of hope in the fact that Hermann Braun, in Theodor Dreher's Mercedes racing car, once again improved on his own record from the previous year in the eighth Semmering race with a time of 7 minutes 47 seconds or 77.1 km/h and secured the trophy for the best time across all categories for Dreher. With a time of 7 minutes and 58.2 seconds or 75.3 km/h, Willy Pöge came second overall.