Yes, it could be done now, by agreement between vehicle owner and a player who would like to rent a car. Anyways, there should be a contract made with conditions and punishments for not returning vehicle back in time (For an e.g. player signs a contract with such condition like "If I do not return the vehicle on <date> on purpose, I agree to be sued in the court of law and I agree to return the vehicle and to pay off court fees and moral compensation to vehicle owner of 100% renting-price per day (Signature of player who rents a vehilce here", or something similar to this) which would protect vehicle owner from stealing a vehicle by renting it.