Recently, I asked my colleagues if they had ever been startled by a robotic driving feature. One described the unpleasant sensation of automatic braking in an Infiniti Q50 Hybrid, which would suddenly slow her down in front of a tight turn, bringing her close to getting rear-ended by the New Jersey drivers behind her. Another had been jolted by the aggressive beeping of his Hyundai rental as it warned him not to stray into a nearby lane. The father of a third routinely started his Toyota Camry with the key fob inside the house, drove to work, and found he couldn't start the car when it was time to drive home. Some 40 percent of American drivers have had a similar experience with what the industry calls "advanced driver assistance systems," or ADAS, according to a survey by Daniel McGehee, director of the National Advanced Driving Simulator at the University of Iowa.

A Tesla Model S electric vehicle is shown in San Francisco, California. Tesla Motors says the Autopilot system for its Model S sedan "relieves drivers of the most tedious and potentially dangerous aspects of road travel." The second part of that promise was put in doubt by the fatal crash of a Model S earlier this year, when its Autopilot system failed to recognize a tractor-trailer turning in front of the vehicle. Tesla says the driver, Joshua Brown, also failed to notice the trailer in time to prevent a collision. In Tesla's own words, "the brake was not applied"--and the car plowed under the trailer at full speed, killing Brown.