I got to thinking about this, and if you're talking about turning a corner, like an intersection, a center somewhat outboard of the inner rear wheel would probably work best.  If you want to make just one turn like that, then changing the center point might pay off.  A subsequent turn in the other direction would rely on being able to animate the change.

If you want to try changing the center point, select the body, or the equivalent of the hip, chassis maybe.  Go to top view and open the joint editor (under Windows menu).  A green cross will appear.  As you hover your cursor over it, it will change to a bull's eye.  Then you can grab it and reposition it.

John