A video posted to YouTube last year provides proof that some people can't be trusted behind the wheel even when their car is doing all the driving. In the clip, the driver tests the automatic cruise control and lane assist in an Infiniti Q50 by hopping into the passenger seat as the car hurtles down the autobahn in Germany. Who would be liable in an accident – the carmaker or the driver? Several carmakers are preparing to introduce technology that will let vehicles take even greater control of steering, braking, and accelerating on stretches of highway. But these vehicles are increasingly being designed to keep an eye on the driver after he or she has handed over control.