As to the model, honestly it was just one quick thought in a stream of conscience purposely meant to be a contrast to the sharing model, or leveraging an under utilized asset - nice phrasing.

A company out to get me free parking is a company after my own heart. In no way was I challenging the AirBnB/sharing/your model, I agree with you and pg the model I describe would not work specifically b/c "shelling out dollars", yet there is value if a valet model cost $18 once and a trip was longer than 48 hours, which sounds like your not meeting a demand so much as your making one.

Keep working on great things.

I think this only works if the benefits outweigh the potential costs. Crashing a car, getting a rental, and purchasing a new car are all unwanted headaches that are more likely in this model vs some screwing up a room in the airbnb model.