Need For Speed: Shift Demo
The most recent version of Need For Speed, precariously titled one consonant away from profanity, "Shift", now boasts a PC demo. There aren't many mirrors up yet, so I'm going to suggest you get it from here. It's 1.13gb, and features racing cars, and the tracks that love them. I'll update that link when a more sensible mirror list can be found. UPDATE: UK mirror here.