http://www.iracing.com/
I was told about this site by a friend tried it at his house and am completely hooked. I have tried to play games on x-box 360 and I was disappointed because the races would have 3-4 12 year olds that turned the thing into a demo derby.If you like online racing than this game is it. This sim is different first its a paid site and 2 there is a licensing system that is rated by youre finish time but also if you hit anything or anyone you lose points meaning that someone who intentionally hits someone goes now where. Theres actually a rule book just like a sanctioning body. The game play looks amazing I just ordered a logitech momo racing force wheel and a newer video card so that I can play.
Good preview here to explain how system works http://www.youtube.com/watch?v=zbAC-PV3lZI