The game is super fun!
I really liked the idea and the execution, it shows how a simple, a little bit crazy idea can turn into a very fun experience. I think the game would be just fine with just happening on the flatground, but You added the Highway mode which adds... well it adds another dimension to the game and it is super awesome that it was added.
When it comes to issues found during my playthrough I guess the only thing that was a slight problem for me were some visual aspecst, the Z-fight between road and train tracks and also the buildings looked a little bit jittery for me. Apart from that I didn't face any problems and the game actually performed well and seemed to be technically well-made.
While all assets were fitting well, the absolute standout is the music that is simply PERFECT for this game. Some people will have something against pre-made assets, but I think that choosing the right things to use is a skill on its own, and You did great in this department.
When it comes to potential improvements for a post jam future, I wish there was some kind of power-ups like system that would for example turn on slow motion or speed up cars, make the road wider or tighter, turn the road into slippery ice etc.
Despite being mostly a fan of puzzle games, a'la Riven etc. I really enjoyed the game. Keep up the great work and good luck in this and any future jams!