Drivers in the United States grew more skeptical of self-driving vehicle technology in the past year, according to J.D. Power's 2017 U.S. Tech Choice Study. At the same time, drivers continued to express interest in driver assistance and collision protection technologies, which often involve some automation.

Compared to the 2016 study, respondents in Generation Z (those born between 1995 and 2004) were 11 percent more likely to say that they "definitely would not" trust self-driving technology. The share of pre-boomers (those born before 1946) showing distrust in autonomous vehicle technology increased by 9 percent. All generations were more likely to be skeptical about self-driving vehicles with the exception of Generation Y, or those born between 1977 and 1994.

"In most cases, as technology gets closer to becoming reality, consumer curiosity and acceptance increase," said Kristin Kolodge, executive director of driver interaction and human-machine interface research at J.D. Power. "With autonomous vehicles, we see a pattern where trust drives interest in technology, and right now the level of trust is declining."

Two highly publicized crashes involving self-driving vehicles have occurred in the U.S. since J.D. Power's 2016 U.S. Tech Choice Study. The first, which occurred a month after that year's study was released, killed the driver of a Tesla Model S. The vehicle's semi-autonomous Autopilot system—which can control accelerating, braking, and lane-keeping—was activated when the vehicle collided with a tractor-trailer crossing the road. On March 24, one month after the J.D. Power study was fielded, a driver collided with an Uber Technologies self-driving vehicle which was being tested in Tempe, Ariz., knocking it onto its side.

Proponents of autonomous vehicle technology point out that these crashes have been infrequent compared to the rate of crashes caused by human error. A review of Tesla's Autopilot technology found that it was not at fault in last year's fatal crash, and the automaker stresses that drivers should continue to pay attention to the road and keep their hands on the wheel when the system is activated. Police faulted the human driver in the crash involving the Uber, issuing her a citation for failing to yield.

Younger drivers are much more accepting of autonomous vehicle technology, a finding which has been consistent since J.D. Power introduced its Tech Choice study in 2015. Fifty-three percent of Generation X and Y respondents said they would be interested in having a predictive vehicle assistant, which anticipates a driver's needs. Forty-five percent said they were interested in limited self-driving technology, while 43 percent were interested in fully autonomous driving technology.

Only 12 percent of baby boomers (those born between 1946 and 1964) said they were interested in a predictive vehicle assistant. Ten percent expressed interest in a limited self-driving vehicle, while 7 percent were interested in full autonomy.

"Along with collision mitigation, there are many benefits to autonomous vehicles, including allowing those who are unable to drive in today's vehicles to experience freedom of mobility," said Kolodge. "Interestingly, though, 40 percent of boomers do not see any benefits to self-driving vehicles."

Despite the increase in reticence toward self-driving vehicles, drivers continued to show interest in features designed to assist drivers and prevent collisions. Asked to select which features they would be most interested in before learning the price, 73 percent chose smart headlights, 71 selected a camera rearview mirror, and 68 percent said they would probably be interested in an emergency braking and steering system.

Thirty-one percent of respondents said they would be willing to pay $700 more for emergency braking and steering technology. Last year, 20 automakers representing nearly all U.S. automakers signed an agreement with the National Highway Traffic Safety Administration to make emergency braking a standard feature on their vehicles by 2022.

"As features like adaptive cruise control, automatic braking, and blind spot warning systems become mainstream, car buyers will gain more confidence in taking their hands off the steering wheel and allowing their vehicles to step in to prevent human error," Kolodge predicted.

The youngest drivers were most likely to express interest in mobility alternatives. Fifty-six percent of Generation Z respondents said they were interested in ridesharing or unmanned mobility, where a vehicle would drive on its own to predetermined locations. Fifty-two percent expressed interest in journey-based ownership, where the driver would have a stake in a flexible use vehicle fleet. Half of the youngest respondents were interested in mobility sharing or co-ownership arrangements, or the sharing of a vehicle's usage and expenses within a group of people.

Generation Z respondents were also intrigued by the idea of a digital key, which would allow them to activate a vehicle with a smartphone or smartwatch. Forty percent said they would definitely like this technology on their next vehicle, and 58 percent said they would be willing to pay $250 more for it.

Between January and February, J.D. Power's U.S. Tech Choice Study collected 8,500 responses from people in the United States who have purchased or leased a vehicle in the past five years.