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LAS VEGAS — As car companies prepare for a future where autonomous vehicles rule the road, recent incidents have shown they’ll also have to navigate an extra hurdle: road rage from human drivers.

Nine months after Lyft and Aptiv released 30 self-driving vehicles onto the streets of Las Vegas, along with a human driver and a safety operator in each car, executives from both companies were at CES, the annual tech show, giving ride-alongs and sharing what they’ve learned since the launch of the public program last year.

Taggart Matthiesen, head of Lyft’s autonomous vehicle division, told NBC News he’s not aware of any incidents of peopl vandalizing or taking out their road rage on his company's self-driving cars.

“This has been a pretty exciting service for passengers in Vegas, and we haven’t really seen any animosity around that,” said Matthiesen.

One reason, he said, could be the fact that the BMW cars, which use Aptiv technology, don’t fit the typical image of a self-driving car.

“It doesn’t have the big spinner on the top, or what looks like sensors hanging off the sides of the vehicle,” he said. The technology has “been really tightly incorporated in the vehicle itself, so I think that is one aspect.”

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Las Vegas police did not immediately respond to a request for comment as to whether they have received any reports of harassment around the self-driving Lyft vehicles.

The APTIV vehicle with autonomous technology drives on the strip Friday, December 1, 2017 in Las Vegas, Nevada. (Photo by John F. Martin for APTIV) John F. Martin for APTIV

But the threat from other drivers, who may harbor animosity toward self-driving cars for a variety of reasons, has become all too real.

Waymo, the self-driving car spinoff from Google, has operated in Chandler, Arizona, for the past two years, where it has encountered at least 21 instances of harassment documented by local police in the town of 240,000 people.

Those instances include a man waving a pistol at a Waymo vehicle as it passed his driveway, tires slashed while idling in traffic, rocks thrown, and a Jeep that ran a Waymo car off the road six times, according to a review published last month.

“Humans often enjoy confusing computers, especially if they are easy to confuse,” said Karl Brauer, executive publisher at Cox Automotive. “Add in the lumbering, cautious nature of autonomous cars — and their interactions with human-controlled cars are easy to predict. Expect humans to speed around them, cut them off and otherwise show autonomous vehicles little respect.”

The instances of police involvement are rare, considering Waymo vehicles log more than 25,000 miles a day on public roads in the United States. A spokesperson added that the company actively engages with the community and has found Arizonans to be “welcoming and excited by the potential of this technology to make our roads safer.”

Like Waymo, the self-driving Lyft drivers go through extensive safety training.

“First and foremost, their job is to keep everyone safe, so any incidents of them maybe feeling a bit threatened would be reported back and we would figure it out on a case-by-case basis on how to handle a particular situation,” said Gretchen Effgen, vice president of global partnerships at Aptiv. “We maintain really strong communications. There’s an end-of-shift reporting. Thankfully, touch wood, these types of things are not things we have encountered here,” she said.

But as more companies speed toward a self-driving future, they’ll have some more work to do in engaging the public, until it feels like second nature for human drivers to share the road with autonomous vehicles, analysts said.

“The good news? Self-driving cars probably won’t respond with road rage,” said Brauer. “The bad news? Their passengers might be seething at how long it takes to merge or make a left turn.”