Well.
I see this game as more of a prototype.
It needs to be more then this if you hope to get good scores.
I noticed a few problems in this.
1: You don't see enough of the landscape so you tend to misjudge things.
2: If you go down hill fast your car seems to get its front wheel stuck in the engine bay, it drops the speed by half.
3: No way to customize your car? you need good customization's to keep people interested. Upgrades are a good thing, even if its just for the looks its still an improvement.
4: The tracks look the same and this causes repetitiveness and they leads to boredom! That's the last thing you want.
5: Music and sound. The music is the same track, you need more then one song otherwise it will annoy the players.
Anyway, see what you think of the ideas.
I hope i helped.