What does "comfortable" mean for someone in a self-driving car?
That's a key question as carmakers and other players head down divergent paths.
Are people ready to trust a car without a steering wheel and pedals right off the bat? Or would they feel more comfortable being eased along with a step-by-step approach?
In an online survey in April, researchers at the University of Michigan Transportation Research Institute presented 618 people, from various age groups, with three visions: completely self-driving, partially self-driving and no self-driving.
Two-thirds of people reported being moderately or very concerned about riding in a fully self-driving car.
In answer to the question, "Would you prefer that a completely self-driving vehicle still have a steering wheel plus fuel and brake pedals (or some other controls) to enable a driver to take control if desired?", the results were overwhelming: 94.5 per cent wanted a wheel; 5.5 per cent did not.
While 37 per cent of those surveyed were "very concerned" about being in a completely self-driving vehicle, 17 per cent had that same level of concern about riding in a partially self-driving one.
Dr Johanna Zmud, senior research scientist at Texas A&M Transportation Institute, did surveys and interviews in Austin and found a 50-50 split between those who intended to use driverless cars and those who did not.
"They are thinking about 'the car I have now, but sometimes it can drive itself', without thinking this will be a brand-new vehicle and it will be very different," she said.
The Michigan study indicated that drivers 45 years and older were significantly more likely to be very concerned about riding in a fully self-driving car.
Dr Zmud, following up her Austin online survey with interviews, found that regardless of age, people identified as "early adopters" were more open.
Ford said that its initial generation of cars without steering wheels or pedals would be used by ride-hailing and package-delivery services in cities where they could be "geo-fenced", or restricted to operate in specific geographic zones.
Asked whether the no-steering-wheel approach or a more incremental one will win wider public acceptance, Dr Zmud said: "I think it's really too early to tell. I think we're probably going to see both things happening at the same time."