Why Cars Won't be Driverless Anytime Soon

Driving on Interstate 495 toward Boston in a Ford Fusion one chilly afternoon in March, I did something that would've made even my laid-back long-ago driving instructor spit his coffee over the dashboard: I took my hands off the steering wheel, lifted my foot off the gas pedal, and waited to see what would happen. To a degree, the car was already driving itself. Sensors were busy tracking other vehicles and road markings; computer systems were operating the accelerator, the brake, and even the steering wheel. The car reduced its speed to keep a safe distance from the vehicle ahead, but as that car sped up again, mine did so too. I tried nudging the steering wheel so that we drifted toward the dotted line on my left.