Awesome

CarSimulator

A Top Down 2D Car Simulator For Unity

Screenshot

Try the demo:

http://www.jgallant.com/CarSim/

Article that details all of the physics involved:

http://www.asawicki.info/Mirror/Car%20Physics%20for%20Games/Car%20Physics%20for%20Games.html

Source code references:

https://github.com/spacejack/carphysics2d