to find out what cars you can do certain races in just click to enter the race and look at the race rules. if you cant do it in the car you are in it will be flashing red. also, i think in the schwarzwald league A it says not to use modified cars, but i managed to do it easily with a Mercedez-benz SL65 AMG Tuned up to over 950BHP!!! you could also try that i suppose, lol!!! hope i helped ya!