The Ford C100 is a sports racing car, initially built and run as a Group 6 car, but later as a Group C car. The C100 was built by Ford in 1981, and initially featured a 4-litre Cosworth DFL V8 engine, which was replaced by a 3.3-litre version of the same engine in 1983, after the car had passed to private hands. Five cars are known to have been built. Although the cars were often very quick in qualifying (when they had been fully developed), reliability problems plagued them, and restricted their successes to two Deutsche Rennsport Meisterschaft victories in 1982, and a single Thundersports victory in 1983. Following the end of Ford's involvement in the C100 project in 1983, Zakspeed modified one of the chassis into the C1/4, which used a 1.8-litre turbocharged in-line 4 from their Group 5