I wanted to teach myself custom movement in Construct 2 so had a go at making some top down racing physics. Quite happy with the results, super easy to tweak settings to get different car types etc.
http://youtu.be/sKhPdPvHv_E
I used a bar connected to the car which rotates to the angle of the car body with a lag, the lag is increased the faster the car travels. This determines direction of motion and the lag speed can be adjusted to create more or less grip.