I'm looking for a single word or short phrase describing a person who is in possession of something, but isn't necessarily the owner, or the sole proprietor. This is somewhat specific to cars, as I'm trying to use it to describe the contact for the vehicle, but in a way that conveys they have the vehicle.
For example: "He's the _______ of the vehicle", or "Vehicle _________: John Smith"
The tricky part about this one is that "owner", "seller", and "dealer" may all be true, but may also all be false (what if the owner and seller is the brother of the guy who actually has the vehicle in his possession?) Or with dealers, the dealership technically owns the vehicle, so it's misleading to say that Salesman X is the "owner" of the vehicle.