This was made in like 3 days. I couldn't figure what stuff I could make happen in the game. If you could come up with some ideas that would be great. :)
Viewing post in T.A.C.S. Totally Accurate Car Simulator jam comments
In terms of gameplay, maybe some stunt mechanics like you see in GTA V, some racing against AI or having other cars/people on the road and completing tasks like "get to point A in X time without killing Y civilians". I'd look around other similar car games and played them a bit and see what they do well + what is missing, and then I 'd incorporate that missing part in here as well as the best of the things they do well.