Who's driving? Autonomous cars may be entering the most dangerous phase

Autopilot controls are not yet fully capable of functioning without human intervention - but they're good enough to lull us into a false sense of security

When California police officers approached a Tesla stopped in the centre of a five-lane highway outside San Francisco last week, they found a man asleep at the wheel. The driver, who was arrested on suspicion of drunk driving, told them his car was in "autopilot", Tesla's semi-autonomous driver assist system.

In a separate incident this week, firefighters in Culver City reported that a Tesla rear-ended their parked fire truck as it attended an accident on the freeway. Again, the driver said the vehicle was in autopilot.