The way I see it, it would not change things fundamentally. If we assume the ownership model is pretty much like cars we have today, only driverless, then it would not change things like congestion in peak hours, parking in the city, shopping center and such. Sure the computer can optimise traffic flow and speed: but only to a certain safe limit: in the complexity of the city with lines merging, flow changing from 4 lines to 2 etc, there will be a limit to speed and I don't think we'll see cars running around at 200k an hour. ... Also even if no attention needs to be paid to doing the actual driving, it does not eliminate commuting time: sure the commute is a lot more comfortable, but you'll still be sitting in the car for an hour or so.