Race Driver: GRID
This demo is like -WHAT?- un-be-lievable, the "Gears of War" of current racing games. Amazing (and I mean photorealistic) graphics, crazy controls that are hard and fun at the same time, constant camera movement, car damage, speed and DID I MENTION THE GRAPHICS? Even the game menu looks like the DiRT menu on steroids, combining stats, announcements and the actual game graphics seamlessly. Also, the "instant replay" gameplay option that allows you to repeat the last few seconds of the race is the most useful thing I've seen in a racing game. I don't know if this has been done before (it probably has), but it certainly is a great addition to the game since it is pretty hard, especially if you are used to Colin McRae games (or the NFS series, although I skipped the last five games or so). Surely it is not GT4-hard hard, but still challenging.
Download GRID demo