Best racing games in no particular order:
* iRacing - Online game, serious but great physics and standard of racing;
* rFactor - Community-driven game, my favourite combo is Mallory Park with classic touring cars <3;
* LFS - High quality physics if a little content-free;
* DiRT 1 only - fantastic rally game and the rallycross is great fun;
GRID is wholly unrealistic (for example the R10 has only 5 gears and manages to do 260 when without the Sarthe chicanes the record is 240...). Shift is filled with so much graphical bleh you can't see what you're doing and GRID 2 is an arcade game.