How about adding a car key to your inventory, and if you click it it wil spawn your car with all items inside to the same location you left it in, but on the different server, and while the key hasn't been used leave the car in the original server. could that be possible? this could add to realism, you could for example implement lockpicks which you could use to steal someone's car. and when picked the car would revert to the original system so that nobody owns it anymore, so that it's more worthwhile to build a car from scratch then to steal one. or perhaps it could make a new key for the new owner. this really doesn't take away any realism and would still appeal to the people that want to move to different servers. and the lockpicking could be usefull so nobody can steal your car and flee the server. some kind of car alarm could also be funny for an interrupted or failed lockpicking attemt. you won't be so eager to steal someone's car when you know a horde of zombies could be coming your way if you try :D.
