Enjoyable with good physics, has potential.
I really like how this game plays, it's enjoyable and challenging.
I do have some suggestions to make it more enjoyable:
-Make it so that if you don't get podium standing you can reattempt the race. It's annoying for the gamer to have to restart at the beginning. You could have race entry fees, and when the gamer is out of funds their track day is over. This would mean longer average play time.
-I Looove how the cars get all squirrly if you put a bigger engine than tires can handle, the drifting is a wonderful touch! (not a suggestion per se, just wanted to mention.)
-The drag on collision with the rails is frustrating. There should be two levels, a slowdown when you rub against it (like running on grass) and then an actual collision-like drag where you lose most momentum. Also make it easier to get off the rail.
-I'd love to see areas on curves which have marbles on them halfway through the race. (marbles=balled rubber worn off tires FYI anyone reading this.) Could be an advanced level/option.
-Variable sound during acceleration.
-Adjust the speedometer and engine ratings to be more realistic. I feel like hasselhoff in a car doing 200 mph and it looks like I'm actually doing 60.
-Whatever you end up doing, keep the challenging part of it!
-Up/Down arrows for accelerator/brake.
That's it for now, Great job!