Add Force or Motor Torque .. Which is better for creating a car?

It's easy to lose hundreds of hours modeling realistic physics. Find a level of simulation that you can work with.

For a physical answer, add force can be considered to either push or pull objects. In the case of a car it would be like making the car a trailer since you would be pulling or pushing from a point.

A real car is using the torque from the wheel, then the rotational force of the wheel is passed to the whole car object. So the torque is more natural.

This is highly simplified.

Nonetheless, the difference won't really show in your game.

I have looked into all the tutorials including the new sample assets beta car. All these cars seems to have different awesome features but I personally feel the simple unity car gives the best dynamics for a race car game :)

But it does not use add force it uses wheel collider which is a complex component using torque on wheel like a realistic car. And yes it is probably as close to a car as can be. At least with unity

Actually I am talking about this one : http://u3d.as/content/unity-technologies/car-tutorial/1qU and it uses addForce to the center of mass. I chose this one because it is the most easiest to implement burnout with.