One couple got the shock of their life on a freeway in Los Angeles when they looked over to see that the driver in the car next to them was fast asleep -- in a Tesla still going almost 120 km/h.

Alisha Olivier filmed the other driver through the window of her car while her husband drove them down the 5 Freeway. In the video, a man appears to be slumped back in his seat, asleep, arms crossed over his chest, while his Tesla continues on autopilot.

鈥淥h my God, he鈥檚 totally asleep,鈥 she can be heard saying in the footage. 鈥淭his is crazy.鈥

Clint Olivier told Good Morning America afterwards that it was frightening to contemplate the idea that 鈥渢he guy 18 inches on my passenger side is sound asleep.鈥

Tesla鈥檚 autopilot is meant to assist a driver, not replace one.

The company鈥檚 website says that 鈥渁utopilot is intended for use with a fully attentive driver, who has their hands on the wheel and is prepared to take over at any time.鈥

In this case, the slumbering driver did take over eventually. In the video, he jolts awake after a moment and grabs onto the wheel.

The number of cars with self-driving capabilities on the road are increasing, and concerns about road safety are rising to match it. There have been several documented cases of cars crashing while the autopilot feature is engaged. In 2018, a self-driving Uber struck and killed a pedestrian in Arizona.

Twenty-nine states, including California, have legislation about autonomous vehicles. In Canada, only Ontario allows self-driving cars on public roads.

Clint Olivier says that although the sight was alarming, he鈥檚 aware it could just be part of everyday life someday soon.

鈥淚t was a scary experience,鈥 he said, 鈥渂ut also, hey, this is 2019, and that鈥檚 the future.鈥

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With files from Good Morning America