The Mazda 717C was a prototype racing car built for Mazdaspeed for the 24 Hours of Le Mans under the Group C Junior formula. It was the first sportscar built by Mazda since the ending of their running in GT with the RX-7 in 1982. It used a 2-rotor 13B Wankel engine, similar to the production engine in the Mazda RX-7. The bodywork and chassis were actually built by Mooncraft with assistance from Mazda.
Two 717Cs were entered at 1983 24 Hours of Le Mans, being the only finishers in the C Junior class, and finishing 12th and 18th overall.
The following year the car would be replaced by the 727C. The Yamaha OX99-11 is said to have a similar design from the 717C.