A sports prototype, sometimes referred to simply as a prototype, is a type of race car that is used in high-level categories of sports car racing. They are purpose-built auto-sports race cars, as opposed to production-car based or street-legal, low-volume homologation specials – thus entirely not intended for consumer purchase, or production beyond the fabrication of the (nearly) unique cars entered into races and in race-car competition classes or "formulas", with sufficiently open regulations to allow for vehicles of unique design to partake.
Prototype racing cars have competed in sports car racing since before World War II, but became the top echelon of sports cars in the 1960s as they began to replace homologated sports cars. Current ACO regulations allow most sports car series to use two forms of cars: grand tourers (GT cars), which are strictly based on production street cars, and sports prototypes, which are allowed a great amount of flexibility within set rule parameters.
