that requires huge amounts of rewriting code as stated in another thread.
When you put it that way it sounds overwhelming. What Badspot has said before is that there are two problems that cause the physics to go nuts. Obviously, vehicle physics in general. The second problem is something to do with networking. It's perfectly possible for them to be fixed, it's just that fixing them isn't on the top of the "To-Do List."
It will happen some day. I expect it to be a "milestone update" like the Event System, or Shadows and Shaders.
EDIT: Here we go: