Along with the ability of improving traffic efficiency and reducing crashes caused by human error, one perceived benefit of self-driving vehicles is a boost to productivity. If you don't have to focus on driving, you'll have the ability to do other things instead.

However, a recent study by the University of Michigan Transportation Research Institute suggests that the productivity benefit of autonomous vehicles will be minimal. The key obstacle would be unease with the new technology, with drivers indicating that they would be reluctant to take their attention away from the road.

The reticence toward giving up control of driving to a vehicle was also reflected in a recent survey by Kelley Blue Book. This survey found that most Americans still want the ability to drive, even if a vehicle is capable of driving itself.

In the UMTRI study, researchers Michael Sivak and Brandon Schoettle note that the typical U.S. light vehicle driver spends about an hour a day driving. While some people would be able to put this time to productive use if the vehicle could drive itself, the researchers concluded that 62 percent of American drivers would not be able to achieve this benefit.

A 2014 UMTRI study found that 36 percent of U.S. drivers would be too apprehensive about letting an autonomous vehicle drive, and so would spend the trip watching the road. Another 23 percent said they would refuse to travel in an autonomous vehicle at all. Sivak and Schoettle also determined that 3 percent of drivers would not be able to focus on another task because they would experience motion sickness.

People who indicated that they would put the time riding in an autonomous vehicle to productive use said they would do a number of different leisure activities, with only 5 percent saying they would work. Eleven percent said they would read, 10 percent would communicate with friends or family, 7 percent would sleep, 6 percent would watch movies or TV, and 2 percent would play games.

Even if a person sought to be productive, they might not have time to accomplish many tasks. Sivak and Schoettle determined that the average vehicle trip is about 19 minutes, which would be insufficient for a restful nap or completing much work.

The researchers concluded that autonomous vehicles would only lead to enhanced productivity if people become more comfortable with the technology and automakers take steps to resolve any motion sickness problems. Since autonomous vehicle design would allow for non-traditional seating, automakers would have to ensure that any vehicle occupants would be protected in a crash. They would also have to account for potential safety issues resulting from leisure activities, such as laptops becoming projectiles or coming between an occupant and an airbag during a crash.

Americans continued to crave some control over their vehicle in a survey recently published by Kelley Blue Book. In May, the auto value resource polled 2,264 people on their opinions related to autonomous vehicles.

Respondents were evenly split on how to balance safety and vehicle control. Fifty-one percent said they preferred full control over their vehicle, even if it was not as safe for other drivers. The remaining 49 percent said they would prefer safer roadways, even if it meant having less control over their own vehicle.

However, a majority of respondents said they wanted control over a vehicle to always be an option. While 63 percent thought travel would be safer if autonomous vehicles were standard, 80 percent said they thought people should always have the option to manually drive their vehicle.

Sixty-four percent said they needed to be in control of their vehicle. Sixty-two percent said they like to drive or consider it fun, and the same share said they prefer to drive rather than be a passenger when they're in a vehicle.

Thirty-five percent of respondents said they would only buy an autonomous vehicle when they were more comfortable with the technology. Thirty percent said they would never buy this kind of vehicle, 19 percent said they would only do so if they didn't have the option to buy a non-autonomous vehicle, and 16 percent said they would buy an autonomous vehicle as soon as the opportunity arose.

Kelley Blue Book found that people were most likely to accept autonomous vehicles if the vehicle performed all safety-critical functions and monitored road conditions but also included an option for manual driving. The lack of an option for manual driving, such as the absence of a steering wheel or other controls, was the most significant deterrent among those opposed to fully autonomous vehicles.

The survey found that younger Americans were much more comfortable with self-driving vehicles than older respondents. Respondents between the ages of 12 and 17 were most likely to be comfortable with the technology and expect that it will be available when they are ready to purchase their first vehicle. While only one-third of this age group believed that fully autonomous vehicles will not be available in their lifetime, the share rose to 76 percent in the 51-64 age group.