It's OKish
Normally I like to criticize a game first, but on this occasion I'll work backwards. The game play is simple, the concept works well, it looks nice for a flash game and it's a little bit of fun to play when you have a minute or two.
However, I'm feeling there was no real use to the 3D engine apart from looking good. Having a few ramps, or even a simple bridge would have made it all worthwhile. That, and every craft in the game is so unmaneuverable meaning that if you have to go around a corner that is more than 45 degrees, you either have to come to a dead stop or bounce around the corners, which is what I always did seeing as the physics engine didn't penalize me too hard for flying bonnet-first into a wall. That, and the game pretty much boils down to who's in the fastest car, seeing as all the AI opponents did what I did and bounce around the corners.
Finally, when I said it was good to play for a minute or two? That's how long it took for me to unlock everything. Making the tracks longer/adding more and harder to get stuff would increase the game's length dramatically.
Apart from that, it's a good game.