I'm not much of a mobile or racing game fan but I think you have a decently polished indie app here. I admit I just put in random single characters for the nickname, email and password fields. No offense but I don't wanna give out my email for a jam game, and I'm too lazy to make a temp email address.
The controls were fairly responsive, and its neat how there were multiple cars, maps and game types.
The main menu had decent pixel art and polish, the only thing that felt a bit weird was how it would take a few seconds to transition between game type options on the bottom section of the main menu. Maybe its some workaround for being unable to properly change which buttons open which submenu, but the lowering and raising of the game type selection felt a bit too long. I mean its a neat effect, but I could imagine it becoming annoying if you were only interested in game types further down the list.
Also I don't know what it was specifically but the night time map in the police game made it hard for me to focus. Perhaps it was that I had the game open in full screen and the constant street lights moving over top of the cars combined with the darker color palette made it harder to see.
Overall a decent mobile racing game, seems like you've been keeping up with updating it. Good work!