Look, no hands, One day every car may come with an invisible chauffeur

DRIVING THROUGH SILICON VALLEY on freeway 101 in busy Friday lunchtime traffic, Google’s Chris Urmson flicks a switch on the steering wheel. A green light comes on to tell him and your correspondent in the passenger seat that the Lexus SUV is now driving itself. A Jeep cuts across it, brakes and exits to the right, followed by a Toyota pickup truck that gets rather close. Each time the Lexus backs off smoothly, maintaining a sensible distance, then accelerates again once the road ahead is clear.