That's really impressive for a first jam entry! I was going to say that the movement was too slow and that you couldn't catch up to your enemies... until I realised I could just buy a better engine with the starting iron; it's really clever the ways you're allowed to improve your vehicle. 

I would say the economy is a bit out of whack; maybe have things increase in price as you add more of them? Otherwise you have too little at the start and too much later on. This also might not be easy to implement, but near the endgame it'd be nicer if the enemies where closer to you (could be done by using complex AI, a decreasing play area like in Battle Royales, or cheating and just teleporting the enemies right in front of the player, just out of view).

The music was really well done, and helps get the players just in a mood to wreck some rival cars! I noticed the main menu music doesn't loop?

That was really fun! Nice work. I love the idea of building up your vehicle as you destroy other vehicles, taking their parts with you. I found the vehicle difficult to control and needed a few tries to get started.