Shift, Dirt 2, are installed in my pc right now and are awesome.
I agree with these two.
Dirt 2 is just fun. It's not hardcore sim, but it's awesome with a wheel!
I'd rather use my G25 and h-shifter with sim games, but I still definitely enjoy Dirt 2, and it has enough realism to at least not detract from the experience.
NFS: Shift. Now that, that is an experience.
If you search some online communities, there is just a TON of setting and internal physics parameter modifications that completely brings out the underlying hardcore sim engine.
But it's entirely enjoyable by default as well, but the first thing I did was look up G25 profiler settings and in-game settings, and that led me to more modifications. The game was new so I was following as the community slowly evolved and came up with better and better solutions. I need to load the game back up some time soon and see how far the modifications have come, especially with recent official patches.