Im gonna try one more analogy today, then I'm gonna start drinking.

Say you've got a nice set of wheels on top of your xterra's rack. They're not geared, just free-spinning. There's a long conveyor lowered lnogitudinally atop the wheels atop your X which will match its speed. It will even put weight on the xterra, say 1000 lbs. Will you be able to drive forward?