Is it your voice when the countdown is going down? I was kind of expecting a human voice for the car noises, too! As it stands it is a bit silent, though. More sounds would be appreciated! I'd love to hear a "vroom-vroom" when you pass other cars!
I liked how you interpreted the theme. It doesn't have any repercursions for the gameplay, but sometimes it's enough.
I do have some problems with the game, though. I feel that my car has MUCH less acceleration but MUCH higher top speed than your adversaries... It makes them feel less like your equals and rivals, and more like artificial obstacles. I would have their cars match ours more closely.
There are a few bugs, but this is a jam game, so it's no big deal. In the Rookie course there must be some sort of check that sometimes does not get triggered, as after a while in the race (in 1st place) I went all the way down to last place without any car passing me. I also went through the finish line and the next lap didn't begin. I had to restart a race that was apparently going really well! Also, it's a bit odd (and it doesn't feel very good) that if an adversary car touches you you immediately stop. It's understandable when you hit them from behind... but it feels really odd and unfair when they hit you from behind you and they keep their top speed
Overall, though, it's a pretty good game! Good job!