Has to be iRacing. Probably the most realistic Racing SIM you can play on the PC. The players are serious about it to, with crazy racing rigs like this,
As for a more arcade experience, I really enjoyed Split Second: Velocity.
The first racing game I've played was Need For Speed: Carbon and I recommend it if anyone wants to play an arcade-type of racing game.
It has some nice missions, very beautiful and interesting places chosen for the tracks. It also has nice graphics for the time it was released, and damn those cars are sexy!
Has to be iRacing. Probably the most realistic Racing SIM you can play on the PC. The players are serious about it to, with crazy racing rigs like this,
As for a more arcade experience, I really enjoyed Split Second: Velocity.
I like Need For. Speed Most Wanted on PC the most. Although I admit that I don't really venture out that much when it comes to racing games on PC. I play racing games a lot more on consoles.