Bingo! Step 1) Only able drivers are allowed to rent, with hands on wheel and like you mentioned ZipCar style pickup Step 2) Car will Come to you driverless,

Bingo! Step 1) Only able drivers are allowed to rent, with hands on wheel and like you mentioned ZipCar style pickup Step 2) Car will Come to you driverless, but you still need to drive. This car will drive very slow during summon. Since no one is inside the car, the risk to human lives are reduced (but still exists for other people) Step 3) Driverless, but limited to certain blocks, weather conditions Step 4) A more expanded version. But all of these appear years away.