I've moved and used vehicles around Europe and as there is no record of entry exit you can go back every 5-6 months or so, then the poeriod starts again. You need the cars UK MOT, tax and insurance valid. I've kept cars until the mot is due then re registered them, as I didn't want to drive across Europe for an MOT test.

If its obvious its parked up in the same spot for 6 months your asking for trouble I would think. If you had the intention of staying and importing the vehicle when you arrive you're supposed to do it as soon as possible.