Production car racing is the exception, custom build race car series are the norm. Even though Touring car and Sports car racing exist, they would be more of a

Production car racing is the exception, custom build race car series are the norm. Even though Touring car and Sports car racing exist, they would be more of an analog to the (hardware manufacturer supplied) overclocking scene, than what is actually required for daily use by professionals, who don't want to sit in cages void of any comfort for endurance races. https://en.wikipedia.org/wiki/Production_car_racing https://en.wikipedia.org/wiki/Production_car_racing