Everyone who's saying GRID is realistic need to get their heads checked.
The driving physics are pure arcade. If that's your thing, then I have no doubt you can have a lot of fun with GRID. :thumbsup:
If it's realism you're after, look for Race07, GTR2, Rfactor, liveforspeed, Richard Burns Rally, Iracing,...
These sims really need to be played with a descent wheel and pedal set-up though.