DETROIT — From a technological perspective, the future of autonomous vehicles is bright.

From a pragmatic perspective, there are a few basic human hurdles.

Like motion sickness. A new report released Wednesday by the University of Michigan Transportation Research Institute projects that 6 percent to 12 percent of American adults will experience moderate to severe motion sickness while riding in driverless cars.

And for the lion’s share of those people, it will happen most times they’re in a car, according to the report.

“By switching from driver to passenger, by definition, one gives up control over the direction of motion, and there are no remedies for this,” report authors Michael Sivak and Brandon Schoettle wrote.

The report illuminates the very basic human issues that threaten the momentum of the autonomous car movement, even as industry analysts like Morgan Stanley’s Adam Jonas project a future society in which driverless cars are the new normal.

On Tuesday, in fact, Jonas issued a report outlining a future “autopia” with “roving fleets of completely autonomous vehicles in operation 24 hours/day, available on your smartphone.”

He suggested that in this “shared autonomy” world, driverless cars will be available for 1/10th the cost of taxis, with riders simply summoning vehicles with a few taps on their phones.

In this new world, Jonas said, public transit systems such as subways are “at risk of being progressively decommissioned” because they’re too expensive to operate.

A Manhattan without subways. Skeptical? You should be.

This futuristic scenario is grounded in some semblance of reality, if only because autonomous cars are inevitable and will dramatically reshape the industry.

Tesla Motors CEO Elon Musk told a group last month that it’s possible that one day driving a car will be illegal because it will be so dangerous compared to simply allowing software to drive.

But the human implications of a transition to a fully driverless world are much more profound than Jonas and Musk acknowledge. Just take a look at the UMTRI report.

Although riders in self-driving cars would give up manual control over the vehicle’s motion, there may be ways automakers can reduce the chances of motion sickness for riders, the researchers noted.

For example, “the ability to anticipate the direction of motion” and “the degree of conflict between vestibular and visual inputs” are additional causes of motion sickness.

“These two factors are influenced by the extent of the visual field, the direction of gaze and posture,” the UMTRI researchers wrote.

One way to mitigate motion sickness would be to design driverless cars in which the passengers can lie completely flat on their backs, the researchers said.

Other options would be to maximize riders’ ability to see outside the vehicle, orienting video screens straight ahead, avoiding swivel seats and limiting head motion.

Fully driverless cars are still years away, perhaps even decades away. The last-mile problem is a serious issue for the industry. You can make a car that handles 99.9 percent of scenarios on the road, but what happens in the 0.1 percent of times when the car doesn’t know what to do?

Despite the challenges, however, autonomous driving technology is already creeping into cars — and that’s a good thing.

Musk said last month that Tesla would upgrade its cars within three months to allow for hands-free highway driving. General Motors plans to offer similar technology when the Cadillac CT6 sedan hits showrooms later this year.

Mercedes, Ford, other automakers and suppliers such as Delphi are also working on major autonomous vehicle technologies.

This technology will make the world safer. But it’s imprudent to proceed hastily without considering the basic human implications of the transition, not to mention the legal, financial, social, safety and political reverberations.