SAN FRANCISCO — By now, seeing one of Google's experimental, driverless cars zipping down Silicon Valley's Highway 101, or parking itself on a San Francisco street, is not all that unusual. Indeed, as automakers like Audi, Toyota and … Imagine a city where you don't drive in loops looking for a parking spot because your car drops you off and scoots off to some location to wait, sort of like taxi holding pens at airports. Or maybe it is picked up by a robotic minder