There is quite a cool new racing sim in the works by the guys who developed NFS: Shift. Some of the guys at the dev team there didn't like the idea of making a game with great physics and then "dumbing" it down a bit for younger people to play. So with C.A.R.S. they are focussing solely on making a realistic driving simulation experience.
I have been a member of the donator community for a few months now and have enjoyed trying out the weekly released Alpha versions - here are some videos of mine from some of the earlier alpha builds:
Formula B (Formula 2), three laps round Bologna (Imola):
Same track, but in a 1968 Lotus F1 car:
Since these videos the alpha version has gotten the Caterham 7, Arial Atom, Formula 1, GoKarts along with quite a few other cars, particularly Le Mans cars.
Oh yeah, and the old stig (Ben Collins) is helping with the development by providing feedback on how the physics compare to real life. :D
You can check out the website for this project at WMD Portal
Let me know if any of you chaps want to see vids of any particular cars and I will try and make them for you.