This is a really cool concept, and if it's something you're looking to expand upon, I have a few suggestions (aside from the obvious bug fixes and allowing the game to run in the background):
1) More tracks - seems obvious, but the simple track here gets boring after 20 minutes or so, and variety would be appreciated. This would also make it more meaningful to have the different cars specialize in different things.
2) Car customization - Let me spend my money on some cosmetics. New paint jobs, stickers, particle trails, neons, etc.
3) Let me set my own path - Admittedly this may be entirely outside of the scope of a game like this, but with additional courses I would love a feature where I could draw my own path around the map and the car would attempt to follow it. This could even include things like manually telling the car when to start braking and when to start accelerating. It would be really cool to perform better at a track not simply because my numbers have been upgraded but because I have drawn a cleaner line around the track.
I hope you'll continue to work on this even after the Game Jam. I think it's a concept with a lot of potential.