Nice game! Very polished for the amount of time. A bit of playtesting feedback rather than criticism because I think you did really well but I see you plan to take it further:
Summary: Boon/nerf mechanics are tricky. Sure as anything, I didn't get bonuses balanced right in my own game!
Example 1: Boons make handling better. But boons make initial handling less fun.
Example 2: Dirt and sand slow you down. But the trajectory is a straight line, so actually, "track" becomes lucky speed-boost tiles.
Example 3: Winning the race nets you rewards. But if you need help, you are locked out of boons.
But overall, fantastic stuff!