if you got a raven Model S you can get a CSS adapter and Tesla can also flash you european maps (they do it for the armed forces all the time).
But the real issue is that you a) need to ship the car back to the USA for warranty related stuff and b) you need to overhaul the car to register it in europe i.e. fog lights, amber indicators, inspection costs, MOT etc.
Easier to sell the car and buy a second hand one in europe.