With the improved Grand Prix car and the 300 SLR (W 196 S) racing sports car based on it, the Racing department then actually did go out in 1955 to get the two titles. Alongside World Champion Juan Manuel Fangio, Neubauer brought Briton Stirling Moss into the team as second star. In the course of the 1955 season, Peter Collins, Werner Engel, John Fitch, Olivier Gendebien, Hans Herrmann, Karl Kling, Pierre Levegh, André Simon, Piero Taruffi, Wolfgang Graf Berghe von Trips and others drove for Mercedes-Benz along with Fangio and Moss.
The 1955 racing season opened with the Grand Prix of Argentina, a hot-weather race from which Fangio emerged as winner. Fourteen days later he also won the Grand Prix of Buenos Aires. On this 30th of January 1955, four Silver Arrows took the start with the three-litre engine which was also to be fitted in the new Mercedes-Benz 300 SLR racing sports car. Juan Manuel Fangio and Stirling Moss scored a double victory in this high-speed test, and Karl Kling came in fourth.
The Mercedes-Benz 300 SLR had its competitive premiere on May Day in the Thousand Miles of Brescia. Four of the new cars lined up at the start, and the young Briton Stirling Moss won the race with his co-driver Denis Jenkinson - the first foreigner since Rudolf Caracciola (1931 winner in a Mercedes-Benz SSKL) to do so. Moss posted the best time ever stopped in the Mille Miglia: ten hours, seven minutes and 48 seconds, which figures out to an average speed of 157.65 km/h. Fangio, driving alone, came in second.
The W 196 R Grand Prix racer with its different wheelbases and body versions featured a large range of variation. Which version was used depended upon the peculiarities of the circuit, the strategy chosen and the likes and dislikes of the respective driver. Common to the individual versions are technical details like the swing axle with low pivot point and the eight-cylinder engine.
In the 300 SLR, at the end of May Fangio won the 18th Eifel race before Moss, and also won the Belgian Grand Prix in June in a W 196 R. Disaster followed these triumphs, in June, in Le Mans, where three 300 SLR started: Pierre Levegh's racing sports car was involved in a collision owing to a risky manoeuvre by another car; his 300 SLR was hurled into the stands; the disaster claimed 82 lives and injured 91 persons. Under the impression of this horrible accident, Daimler-Benz decided to withdraw Moss, who was in the lead, from the race. The tragic accident overshadowed the rest of the season.
In the Dutch Grand Prix a 1-2 win by Fangio and Moss in the W 196 R followed. The young British star Stirling Moss then won the British Grand Prix in a short-wheelbase W 196 R, followed by Fangio, Kling and Taruffi. This was a sensation for the British public: for the first time an Englishman had won this major race in his home country.
In the sports car race for the Swedish Grand Prix, Fangio again finished ahead of Moss in the 300 SLR; Karl Kling complemented this double victory with a win in the sports car class in a 300 SL. One of the two 300 SLR Coupés designed by Rudolf Uhlenhaut also was along for the ride in Sweden as a training car. The Coupés were never entered in a competition though.
In the competition for the Italian Grand Prix on 11 September 1955 the W 196 R Silver Arrows gave their last performance. As four of the season's events had been cancelled, this simultaneously was the first appearance made by the aerodynamically faired, streamlined racing cars in 1955. The W 196 R with exposed wheels competed in all the other races. After extensive alterations, Monza presented itself as a high-speed course on which the field passed the grandstand twice. Because of the high average speed allowed by this course, Neubauer decided that Fangio and Moss should start in the streamlined car with the long wheelbase. Kling got a monoposto with a conventional body and medium wheelbase, Taruffi started in a short "Monaco" car. Unchallenged, Fangio brought home his last victory for Mercedes-Benz, followed by Piero Taruffi, just 0.7 seconds behind him. With 40 points, the Argentinean champion became Formula One World Champion in that season for the third time; Stirling Moss (23) was runner-up.
But it was still not clear whether the second goal of the Racing department for 1955 would be achieved. Alfred Neubauer recalls: "There is just a little blemish on the medal: the racing sports car world championship, also called the 'constructor's prize', hardly is going to end up in our possession. The competition for the 'constructor's prize' was held for the first time in 1953. It doesn't go to the driver, but to the company whose car wins. Ferrari has a clear lead and hardly can be caught - unless a miracle happens."
On 17 September, three 300 SLR took the start at the Tourist Trophy in Northern Ireland, and the miracle longed for by Neubauer came to pass: Stirling Moss and John Cooper Fitch won the race ahead of the 300 SLR of Juan Manuel Fangio and Karl Kling. Third place was taken by Wolfgang Berghe von Trips, who had experience racing the 300 SL, but was driving the 300 SLR for the first time in competition, and André Simon.
The Sicilian adventure called the Targa Florio, in mid-October, finally secured the manufacturer's championship for Mercedes-Benz. Rival Ferrari could not be allowed to do any better than third place there. And so it came to pass - great effort being taken to make sure of it. Eight racing cars and eight heavy trucks as well as 15 other cars were heaved out of the ferry from Naples in Palermo. They had 45 mechanics to look after them. SLR driver Stirling Moss likes to emphasise that he never experienced such a measure of preparation, such precision und logistical effort again during his entire long career.
Neubauer brooded over the tactics: "I had never planned a race more thoroughly and carefully. I mustered all my experience, my skill, my tricks, my love, and invested it in this 1955 Targa Florio." Perhaps the most important plan of the racing strategist involved the change of drivers: contrary to the customary relieving of the driver after three laps, this time the Mercedes-Benz drivers were not supposed to get out of the cockpit until they had completed four laps. Uhlenhaut had the 300 SLR reinforced for the harsh course.
At 7 a.m. on 16 October 1955 the first car started. Stirling Moss took the lead, but dropped back into third place after an accident. Peter Collins took over the wheel of his car and on his first lap with the dented Mercedes-Benz set a new lap record. Now in the lead, Collins handed over the car to Moss, who won by a margin of four minutes and 55 seconds before Juan Manuel Fangio. John Fitch and Desmond Titterington in the third 300 SLR came in fourth behind Eugenio Castellotti and Robert Manzon (Ferrari 860 Monza). Mercedes-Benz managed to pull off the double victory needed to win the manufacturer's world championship - the goal had been reached.
That marked the end of the heyday of the classic Silver Arrows. Prior to the Le Mans disaster Mercedes-Benz already had decided to discontinue the activities of the Racing department following the 1955 season: The expense and effort for the development and production of the racing cars and for providing racing support was immense. Daimler-Benz AG had more urgent need for the energies of the engineers and mechanics to develop new passenger cars. Fritz Nallinger, Board of Management member responsible for Engineering, confirmed this at the ceremony honouring the successful racing drivers on 22 October 1955: "The further development of our product range makes it appear advisable to us to put these highly skilled people to work now, without overtaxing them, solely in an area which is the most interesting to our many customers worldwide, namely the field of production car engineering. The knowledge and experience gained from racing car construction will benefit my employees in this work."
The withdrawal from racing was an honourable retreat at the peak of success: In 1955 the W 196 R racing cars took part in seven events, winning six of them and taking five second places and one third place. The 300 SLR racing cars started in six races, posting five wins, five second-place finishes and one third-place finish. Mercedes-Benz hardly could have dominated the season more clearly. Further successes by factory drivers and private entrants driving
Mercedes-Benz cars complement the results for 1955: Paul O'Shea (USA) in a Mercedes-Benz 300 SL was class D sports car champion in the United States for the first time. O'Shea also won the title in the following two years. Werner Engel secured the European Rallye Championship in his Mercedes-Benz 300 SL in the same season. Armando Zampiero was Italian sports car champion in a Mercedes-Benz 300 SL.
The era of the Silver Arrows on the major racing courses was over for the time being. Many years would pass before Mercedes-Benz returned to championship sports car racing and Formula One. It was a melancholy farewell, as Alfred Neubauer recalls, drawing a line under a grandiose season: The drivers drew white cloths over the cars and said goodbye. "We shook hands once more. Then they drove off, heading for who knows where - Fangio and Moss, Collins, Kling, Taruffi and Graf Trips. And that was the end of it."