Electric car maker Tesla Motors is leapfrogging competitors with a new autopilot system that lets cars change lanes by themselves.

Like other semi-autonomous systems already available from Mercedes, Audi and Volvo, Tesla's system automatically keeps the car within its lane and maintains a certain distance from the car in front, both at highway speeds and on city streets.

It can find a parking spot and parallel park itself, and uses cameras and sensors to warn drivers about potential side impacts.

But analysts say the lane-changing feature is an industry first. Tesla chief executive Elon Musk said the system is also unique because it will constantly collect data from drivers and improve itself. The system will note, for example, how quickly drivers can safely navigate a particular bend in the road or where stop signs are located.

"I think this is going to be quite a profound experience for people," Mr Musk said. "It will change people's perception of the future quite drastically."

He added a word of caution: Drivers need to keep their hands on the wheel, and the autopilot system will chime to remind them if they do not. Drivers - not Tesla - will be held liable if there's a crash, Mr Musk 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," he said. "The software is very new."

He said fully autonomous, hands-free driving is still at least three years away from a technical standpoint, although it will probably take regulators longer than that to allow it.

The autopilot update will be added to around 60,000 vehicles worldwide, including Model S cars made after September 2014 and Model X SUVs. Owners will get the system through a software update starting in North America. Owners in Europe and Asia will get the software update in about a week. People with Model S cars made earlier do not have the required sensors and will not be able to add them retroactively, Mr Musk said.

Only owners who paid the 2,500 dollar (£1,615) charge for the full autopilot system will be able to activate all of the autopilot features, but Mr Musk said the side-impact warning is a safety feature and will be available to everyone. For the next update, Tesla is working on having the car drive itself in and out of garages when it is summoned by the owner.