Man caught sleeping behind the wheel of Tesla on 'autopilot' down busy road

A US driver has been spotted taking full advantage of his Tesla's autopilot by apparently sinking into a nap - much to the shock of the man in the car next to him.

Twitter user Dakota Randall posted a video he said he had taken along the Massachusetts Turnpike yesterday.

"Some guy literally asleep at the wheel on the Mass Pike (great place for it)," he wrote.

"Teslas are sick, I guess?"

The video shows the driver with his head slumped down towards his knees and without a hand on the wheel.

His passenger also appears completely relaxed, leaning back against their seat in a doze.

Meanwhile, the car continues driving along, keeping pace with Mr Randall in the next lane.

While Massachusetts police said there was no law against falling asleep behind the wheel of a self-driving car, Tesla does not consider its autopilot-equipped vehicles to be "self-driving".

Tesla's official position is that its autopilot system still needs active supervision from the driver.