"Imagine you get into an autonomous car and it's sunny outside, your suburban road is empty and you're playing Angry Birds," says Clifford Nass, director of the Revs program.

"An hour later, the car asks you to take over within 10 seconds. Except now, it's pouring rain, there's tons of traffic downtown and the car to your left rear is behaving erratically.

"These are things you would have noticed if you were driving. But now you are dropping in from outer space, basically. We have no idea whether people can mentally prepare themselves for this."

Stanford is researching the design of an in-car briefing feature, in which the vehicle can quickly bring a person up to speed, much like a change of command aboard an airliner.

For more than a decade the Michelin Challenge Design competition has allowed young designers -- from high school students to design professionals -- to anticipate the vehicles of the future. With autonomous cars all the buzz the subject was an obvious choice for this year's challenge.

For contest juror Ben Ebel, a Michelin industrial designer, the encouraging sign was that many of the design entries were for cars that had passion.

"There is a perception of autonomous cars becoming appliances, as merely a device you use to transport yourself," Ebel says. "But we saw devices that had the ability to reflect a driver's personality, the way in which the car morphs between autonomous and nonautonomous."

A key question, he says: Will people still want to do a certain amount of driving, or is the autonomous vehicle of the future just transportation?

"If it's a personalized transportation device, I would think configurability is going to be the biggest part of it," Ebel says. "Certainly, for someone that has a commute, they're going to want to have an area to work. For someone taking a family or transporting items, it needs to be multiconfigurable. So I think you're going to see a lot of that -- a multiconfigurable area."

And comfort is likely to be a premium.

"We can start looking at what a superluxury liner looks like," he says, "like a 787 Dreamliner, or something, and start looking at how we keep people very comfortable over traveling distances -- but still have a place for them to work."

Design firms such as IDEO in San Francisco are taking a holistic approach to the autopilot question.

For example, autonomous cars also could change the way people travel to a vacation.

The fly-or-drive debate for the Los Angeles-to-San Francisco dash would change dramatically "if you could just hang out with your family" while your minivan piloted you door-to-door without the frazzle of Interstate 5, says IDEO partner Diego Rodriguez.

But that's only the beginning. Could an autonomous car pilot an 8-year-old to school or Little League practice by itself? If so, Rodriguez asks, how would the car's controls be designed to prevent the child from taking control of the car?

Ford's Callum sees the possibility of interior design returning to the era of stylized Renaissance horse-drawn coaches. But a big factor in the aspirational vs. appliance question is whether autonomous cars will allow for a sense of "arrival" at a destination.

"If it's a bespoke infrastructure just for autonomous vehicles, then you just have an appliance, because you won't be 'arriving' anywhere. It will just be regimented," Callum says.

"But how cool would it be to arrive at the door of a restaurant, step out and be able to tell the car to go away? There is an element of theater there."

Shiraz Ahmed contributed to this report.