Fun idea, but physics might need some work.
The biggest issue I have is steering, very strange feeling. A quick look at the suspension shows the steering arms in a very odd place, they might need some work, also STEER_ASSIST must always =1, unless its a high downforce car (which its not).
Also, as noted before, the file is far too large. Most cars should be 40MB max, yours is about 370MB!