[jaggederest]

> I'm talking specifically like portions of the trip like the driveway, getting out of the parking ramp, or navigating small alleyways where the car could be parked (where GPS could be weak in the city)

Relatively simple from a conceptual point of view: a human drives it the first time, and later times use sensors to apply basic rules and the original 'instructions' learned from driving it manually the first time.

Extend this to a network of cars sharing route information, and only a small sampling of the population ever needs to drive any given route manually.