The Porsche 956 was a Group C sports-prototype racing car designed by Norbert Singer and built by Porsche in 1982 for the FIA World Sportscar Championship. It was later upgraded to the 956B in 1984. Driven by Stefan Bellof in 1983, this car holds the all-time record for the fastest vehicle ever to lap the famed Nürburgring Nordschleife, completing the 20.832 km (12.93 mi) circuit in 6:11.13 during qualifying for the 1000 km Sports Car race.
Built to comply with the championship's new Group C regulations which were introduced in 1982, the car was a replacement for Porsche's successful 936 model which competed in the previous Group 6 category of the World Championship. The project began in June 1981, and the first prototype chassis was completed on March 27, 1982, in time for the beginning of the World Championship season. Jürgen Barth tested the first chassis at Porsche's private test track.
The 956 features a chassis made of an aluminium monocoque, a first for the company, helping to allow the car to meet the 800 kg (1,764 lb) weight minimum in Group C. The engine is the same as the one used in the Porsche 936/81, the Type-935 2.65 L turbocharged Flat-6, producing approximately 635 hp (474 kW) (originally developed as an Indycar engine; hence the cubic capacity used). The very first dual clutch gearbox was also designed for the 956, mated to a traditional 5-speed manual.
An improved chassis with better fuel efficiency from a Bosch Motronic electric system was developed for 1984, being termed the 956B. In total, twenty-eight 956s would be built by Porsche from 1982 to 1984, with an unofficial 29th chassis built from spare parts by Richard Lloyd Racing. The 956 was also the first Porsche to have ground effect aerodynamics. As a comparison, the ground effects Porsche 956 produced over three times as much downforce as the older model Porsche 917 that raced over a decade earlier.