The 917K models were generally used for the shorter road courses such as Sebring, Brands Hatch, Monza and Spa-Francorchamps. The big prize for Porsche however, was Le Mans. For the French circuit's long, high speed straights, the factory developed special long tail bodywork that was designed for minimum drag and thus highest maximum speed. On the car's debut in 1969, these long-tail (917L) models proved to be nearly uncontrollable as there was so little down force. In fact, they generated aerodynamic lift at the highest speeds.