In this American endurance racing series sports prototypes and GT cars are admitted. Audi developed the R8 GRAND-AM specifically for this championship. Although it is based on the successful Audi R8 LMS, it was modified, however, to comply with the American regulations. The race car for the US market differs significantly from its European brothers in the areas of the bodywork, under floor and rear wing. The engine is also considerably less powerful and the driver aids ABS and traction control, standard in the R8 LMS, are forbidden in GRAND-AM.