Try to imagine a future with self-driving cars. What do you picture? Are you sliding into your own Tesla Model S, or are you calling up Driverless Cars Company X for a ride? Do the cars circle campuses and downtown streets until summoned? Or do they quietly return to driveways and parking lots, ready to be woken up when needed? For all of Elon Musk’s confidence, it is still unclear how self-driving cars will fit into our society.