This brings up the most challenging obstacle on our road to the autonomous-driving future: managing the handoff. For as long as anyone, even Google, is willing to predict, cars will by necessity be semi-autonomous; human drivers will still have to play some role. But figuring out what that role will be is complicated. Are we pilots or copilots? How far out of the loop can we be taken? “We need clear mental models of when you are better at something and when the car is better,” Stanford’s Nass says.