This is better and more easily addressed by car sharing services like car2go than autonomous cars. The more I use them the more I wish for a world where every car was shareable: you need to go somewhere? you simply get into the nearest parked car and drive it to where you want to go. And, unlike autonomy, there are no technical barriers to this, only the will to do it and the economic model to sustain it. Sadly these services seem to be in full retreat now but I will miss them and still hope they'll rise again soon.