When will car sharing catch on?

Car sharing is a system of short term rental that gives you occasional access to a car without the
expense and hassle of owning a vehicle full time.  Globally it operates in more than 500 cities.  When
cars drive themselves, car sharing will be more convenient than ever.  This is because new cell phones
have a GPS system in them and your location will be transmitted to a car dispatcher which will then send
a self-driven car to your location.