As Rosier started with at least 44 years for the first Formula 1 Grand Prix on May 13, 1950 in Silverstone in a 4.5-liter Talbot -Lago, he was in his native already a well-known racing driver who, however, due to its relatively high age was no longer courted by the major racing stables.
Legendary was his win at the 24 hour race at Le Mans in the same year, where he managed the feat on a Talbot T 26GS to sit alone for 23 hours a wheel of the vehicle - then as now almost unthinkable.
Unlike many other drivers of his generation, the career of the garage owner and Renault dealer was not straight. In 1927, he played first motorcycle race on a Harley- Davidson, later sports car competitions on Scap and Talbot.
During the occupation of France in World War II Rosier was active as smugglers for downed Allied airmen in the Resistance. After the war, who had brought many racers and athletes to the most valuable years of their career, he tried to continue to be successful in sports cars and even won on entirely new ground in the Monte Carlo Rally in 1949 in the class up to 1100 cc, together with his son Jean- Louis in a Renault 4 CV.
When Louis Rosier took fourth place at the end of the season behind the three big " F" Farina, Fangio and Fagioli, the experts were surprised. But this result was due to his prudent driving style with the technically inferior vehicle that had ever led him into the points in Bremgarten and Spa- Francorchamps even with the third rank to the winners' podium.
In the following years he had as a racer but less fortunate. In the Formula 1 season, 1951, he was able to drive with the now even more inferior cars only once with the fourth place at the Belgian Grand Prix in the points, which meant 13th place with three points in the final standings. However, he won again this year the rally in Monaco, this time in the class ³ to 750 cm. By 1954, he tried like many other drivers who could no longer compete with the factory teams on a Ferrari 500 in the formula 2, where he at least could finish four races victorious. Thus encouraged, he returned with his Ecurie Rosier, his old Ferrari 500 and developed for the new 2.5-liter Formula 625 back in the premier class. The latter was driven usually by Manzon or Trintignant, he himself stayed with the increasingly technically inferior 500 mostly chance. For mid-season, he joined with a Maserati 250F, the previously Luigi Villoresi had driven to the work team of Maserati in Monza and bought the car end of the season for his Ecurie. But he was down to 1956, the last year of his career on the Maserati Grand Prix of Germany at the Nürburgring fifth.
Encouraged by this partial success won Louis Rosier few weeks later with Jean Behra the 1000-kilometer race from Paris to Montlhery on a Maserati. On the same route Rosier lost on October 8, 1956 at wet track just before the end of the "Coup de Salon ' race violence of his vehicle and crashed into the distance limitations. Three weeks later, Rosier died in a hospital.
The four-time French sports car champion, two -time Rally Monte Carlo winner and fourth overall of the season in 1950 and winner of the Grand Prix, which did not count for the World Cup, reached in his eventful career 18 Formula 1 points, given the few races and the points system, was driven by the then, should be assessed quite higher than today and were in the range of racing driver Maurice Trintignant, also French, who had the good fortune to be able to act as a works driver for Ferrari.
Among other things, on Rosiers initiative, and through his efforts to sponsors was the late 1950s, built his home in the Circuit de Charade. He himself experienced construction and opening of the circuit no longer, it was initially named in his honor in the name of Louis Rosier Circuit.
Posthumously, the French President awarded him the Cross of Merit of his country and thus honoring a racing enthusiast who was extremely versatile in its modest and cool style. No other Formula 1 racers can boast that they have both won Le Mans and the Monte Carlo Rally.