Hi,

I'm also working on a car physics model, and also encountered problems with the hinge, such as wheels turning into the wrong direction or in worst case fly of the car.

The only solution seems to be setting friction to zero, at least in higher speeds,, then, however, you have the problem that when the car drives against another physics object (e.g. a 15kg cone), the car starts flying but not the cone.

I did not worry about suspension yet.