How do I keep momentum after change X (physics)

Well I'm veeery new at physics.

Trying to do a "infinite driver" sort of thing, with a car composed of a body with two wheels attached, "traction" comes from the rear wheel spin. When the car reaches certain X, it's moved to Self.X-5000, so the level loops over itself. Works fine, but there's a noticeable bump in the car motion right after "teleporting". Is there any way to fix that?

Thanks!