JSPC '1983–92

The Mazda 737C is a prototype racing car that was built for Mazdaspeed for the 24 Hours of Le Mans under the Group C2 formula. It was the final evolution of the initial Mooncraft built design dating back to the 717C. It again used a 2-rotor 13B Wankel engine. Two 737Cs were entered in the 1985 24 Hours of Le Mans, finishing 3rd and 6th in the C2 class. The 737Cs were also raced in part of the 1985 World Sportscar Championship season, managing 8th place for Mazdaspeed in the C2 teams championship. In the All Japan Sports Prototype Championship, Mazda was able to come home 5th in the constructor's championship. 737Cs later ended up in the hands of privateers for the JSPC after Mazda replaced it with the newer 757.

Two 757s entered the 1986 24 Hours of Le Mans, but both failed to finish the race due to gearbox problems, marking the first time Mazdaspeed had failed to finish at Le Mans. In the All Japan Sports Prototype Championship season, Mazda was able to come home 3rd in the manufacturer's championship.

For 1987, two 757s were again entered, with one finishing 7th overall while the other suffered engine failure. Along with a good result at the joint World Sportscar Championship and All Japan Sports Prototype Championship event at Fuji, Mazdaspeed was able to achieve 10th in the teams championship for WSC and 3rd in the manufacturer's championship for JSPC.

Two 767s were entered at 1988 24 Hours of Le Mans, finishing 17th and 19th overall, however they finished behind a sole 757 which was able to finish 15th. In the All Japan Sports Prototype Championship, Mazda managed 4th in the constructors' championship.