There are several levels of autonomy, going in stages from driver assistance to full automation. For example, by 2020 Honda is aiming to bring to market a vehicle with a high level of automated capability in highway situations. By year’s end, Volvo plans to put highly automated XC90 vehicles in the hands of real-world drivers in Sweden as part of its Volvo Drive Me program.

Within the next four years, BMW hopes to have cars on the street with midlevel automation. BMW and other companies are also working on driverless prototypes that have no steering wheel, brake or gas pedal.

Still, a world in which fully automated cars are common remains many years away. “It’s all going to be a slow transition,” said Nicole Carriere, director of public relations for Edmunds.com. “There will be a fundamental shift, but it won’t be overnight.”

The spectrum of vehicles eventually coming to market will allow older drivers to consider the types that suit them best. For example, some auto manufacturers are developing semiautonomous systems that give drivers seconds to prepare to re-engage to avoid collision, and will pull to the side of the road if re-engagement is not detected. Experts say such systems may not be optimal for those who take some medications or may have difficulty reorienting themselves.

Keep in mind that driving abilities vary among older adults, said Dr. Nir Barzilai, director of the Institute for Aging Research at the Albert Einstein College of Medicine in the Bronx. “It’s not chronological age that’s important, it’s biological,” he said. “There are 100-year-old drivers who are fine, and some 60-year-olds who shouldn’t be on the road.”

James Kenyon is a Detroit franchise owner of Visiting Angels, an agency that provides nonmedical home care for seniors. From what he has observed, older seniors could have a difficult time adjusting to driverless technology.

“It’s a whole mind-set change for the elderly to have something that they can’t control, and even getting their children to buy into it,” Mr. Kenyon said. “Theoretically, it sounds great, but there are so many possible impediments that have to be worked out, like, if there’s a problem, what do they do?”