Sure, you owe him a car for the duration, the fact that he can get it whenever he wants doesn't change much. If the car you stored goes missing (and you set up

Sure, you owe him a car for the duration, the fact that he can get it whenever he wants doesn't change much. If the car you stored goes missing (and you set up a contract) you'll find you now owe him money. Another interesting thing is that you (a bank) will typically store not one but a hundred cars, and you will lend 90% of those to other people at any given point, in exchange for money. So everyone thinks their car is stored in a garage and they can get it whenever but they probably can't. The system only works because people don't need their cars that much.