Car combat game Gas Guzzlers has been out for ages now, and while a demo for it released even before that, it was apparently pulled. In either case, it's available again now, and possibly even a newer version of it. You can grab the 1.65 GB file at the source.
If you're curious first to learn how the game is, I noted back in my March preview it's polished and fun, but the lack of good mouse and keyboard support are a detriment. Of course, if you don't mind using a 360 controller for this sort of shindig, then by all means dive in.