I mostly agree with this. Any rational business model would probably require some demand and usage based pricing, and if you are using a shared car the same way you would if you owned it (i.e. commuting to work during peak hours, weekend trips), than it should come out to roughly the same cost as ownership. However, in high density urban areas, parking is still a real pain. In my opinion, this is really where the potential for driver less cars is. A dedicated parking spot can be expensive, and street parking can be a nightmare.