I really like the concept and most of the execution, there's just a few quality-of-life things that would go a long way.
1. Sound effects. Probably doesn't need explanation.
2. The ability to run a race with the same car after racing it. I know the point of the game is to build the car and then race with it, but it feels bad to get a super good car build but then not be able to enjoy it for long. Maybe car building and racing could be in separate modes, and all of your built cars enter a garage which you can then take out any of them for any race? And then the current version where you have to scavenge for a single race could be another mode altogether, so then everyone can be happy.
3. The ability to stop scavenging and start the race early if you're happy with your car.
4. A final opportunity at the end of scavenging to replace any car parts, but only with parts that are currently in your inventory.
5. The ability to see your current car and parts' stats while scavenging, so you don't have to remember.
These tweaks would make a really big difference in how the game feels, because currently it's just so close to something I'd wanna sink a lot of time into, but there's just slightly too much resistance from the game itself.