Cool!
Very cool game! Must have taken a long time to make. Very smooth handling and great customization features. Reminiscent of the old Amiga game 'Nitro', which you could check out for more ideas if you don't know it already.
Some suggestions that would make the game better imo:
* bigger screen size (would allow more accelleration)
* perhaps a mini-map feature in one corner
* more powerups on the track, for instance money that could be used at end of level to upgrade the car (tyres, engines, bumpers, etc.)
* Oil pools on the track that makes the car spin uncontrollably for a few seconds.
* AI opponent cars to race against, or multiplayer competitive race mode (ambitious)
Great job, overall. I'm adding this to favorites.