There's a great PC game called rFactor. You basically buy a license to the game for about $30 (it comes with about 6 tracks and 10 cars or something) and after that you can download tons of cars and tracks for free from the community. The game is awesome, extremely real if you want it to be, but it takes a little while to configure it to your liking becuase it's so detailed. After that, there is NO WAY you can't improve your driving by playing it, especially if you have that g25 wheel with the shifter and pedals (it also works on ps3 with gran turismo 5).
Download VIR track:
Download M3 GTR conversion (they don't have e92 M3 yet, this is closest I think):
Good video of the game in use:
The rest of the cars/tracks are great as well, you can get them all from www.rfactorcentral.com
, try out the ones liested in their "hall of fame" section.. good stuff.