Autonomous cars will only really see true potential when they don't need a driver at all... or one in the car. Think one driver, jumping in on 5 or 10 UPS delivery vehicles as they park and launch delivery drones locally, or 20 Google maps vehicles with one remote driver jumping in at roundabouts. While 3 city buses with capacity for 5 or 10 more people each since there's no physical cockpit is promising or not having to pay attention, the true potential is all the things you don't need people for.

The true potential in Autonomous vehicle removes the cost of having people involved with delivery, exploration, etc.

Once the tech is there, you can remove the excess weight and volume of seating, safety mechanisms (mirrors, belts, roll bars, airbags...).

Removing human ergonomics will also allow for more efficient designs per purpose.