Videos posted online appear to show Tesla`s new self-drive mode causing its cars to drive dangerously and speed.
One appears to show a car suddenly swerving off the road after exiting the motorway in the US city of Portland.
Another appears to show a Model S Tesla swerving towards an oncoming vehicle.
Autopilot takes over driving functions such as steering and changing lane.
But Telsa said: "The driver cannot abdicate responsibility for driving."
It said: "The latest autopilot release is a hands-on experience to give drivers more confidence behind the wheel, increase their safety on the road and make motorway driving more enjoyable."
But one Miami driver said his car had sped up to 75mph (120km/h) in a 60mph zone, resulting in it being pulled over by the Florida Highway Patrol, and posted pictures of the tickets he had been issued.
At the time of its release, Tesla chief executive Elon Musk said autopilot was still in test mode.
"The software is very new," he said.
"We`re being especially cautious at this early stage, so we`re advising drivers to keep their hands on the wheel just in case."
The notes accompanying the software update also stated it was suitable only for motorway driving.
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