Would it be possible to have multiple vehicles tied to one key? What I was thinking was when you buy a vehicle the game checks to see if you already have a key on your belt, if you do it ties the new vehicle to that key, and if you don't it gives you a new key. That way if you want your vehicles to have separate keys you just make sure you don't already have a key on your belt when you buy a new one, or if you have them tied to the same key you can still make copies for backup or to share with friends.