I like the concept, especially since you can actually bump into your past selves and it affects them - you haven't just made a simple recording and played it back. I've built quite a few top-down racers myself for commercial clients, and I know how tricky they can be to get to feel good.
The controls for the car are actually my least favourite part of this game. Driving should be fun, a little bit of slip, skidmarks, wheelspin, understeer and oversteer... Your car has little of those attributes, and doesn't really feel like, well, a car!
The view is also far too close to be able to see what's coming. The arrows on the road help a little, but not enough. I failed to beat my first tentative slow lap, and almost gave up when I fell too far behind. As it happened my past-self got to the end of their replay and ended the game.
I know some of that sounds harsh, but it's important to remember this is what games jams are all about: Try something quickly, see if it works. Hopefully learn from your mistakes so you don't repeat them at a bigger scale! It's enough of a challenge just to get a playable game live in 4 days, congratulations on a working game (loads of teams don't get that far).