The Porsche 935 was introduced in 1976, as the factory racing version of the Porsche 911 turbo prepared for FIA-Group 5 rules. It was an evolution of the Porsche Carrera RSR 2.1 turbo prototype which had scored 2nd overall in the 1974 24 Hours of Le Mans.
Beginning with the 1977 season, Porsche offered the 935 to customers which entered the car in the World Championship for Makes, in the IMSA GT championship and in the German Deutsche Rennsport Meisterschaft (DRM). The 935 went on to win the 1979 24 Hours of Le Mans overall, and other major endurance races, including Sebring, Daytona, and the 1000 km Nürburgring. Of the 370 races it was entered, it won 123.
Usually, no other make could challenge the Porsche 935, as due to the availability of customer models, each race at the time typically featured at least five 935s. Racing became entertaining for the crowd at the expense of the diversity of makes. The large turbocharger was controlled by mechanical fuel injection which caused turbo lag followed shortly by a fireball spitting from the exhaust and an enormous amount of power (up to 800hp). The dominance of the 935 was ended by the FIA rules changes coming in effect in 1982, when the six numbered groups were replaced by only three groups, A, B and C.
For 1976, endurance racing had two World Championships: the 1976 FIA World Championship for Makes for Gr. 5 Special Production Cars, and the 1976 World Sportscar Championship season for Group 6 prototypes up to 3.0L. Accordingly, the 935 and the new Porsche 936 were the two-pronged Porsche effort for 1976. Each championship had 7 races, with only Dijon hosting both at the same weekend, while on two other weekends, the races were even run in different countries, which forced Porsche to divide its resources. Jacky Ickx and Jochen Mass were the main drivers, if F1 schedule permitted. Rolf Stommelen, who was recovering from his bad crash in the 1975 Spanish GP, was the backup, along with Manfred Schurti.