Tesla’s Autopilot feature can be tricked into operating without a driver, a US consumer magazine has found.
Engineers from Consumer Reports investigated claims Tesla cars can function without a driver present.
They tested the Model Y on a closed track with an empty driver’s seat over several trips.
The publication found that the Model Y automatically steered along painted lane lines without recognising that nobody was at the controls and concluded the system could be "easily tricked".
Jake Fisher, Consumer Reports’ senior director of auto-testing, who conducted the experiment said the system “couldn’t tell if there was a driver there at all”.
“Tesla is falling behind other automakers like GM and Ford that, on models with advanced driver assist systems, use technology to make sure the driver is looking at the road,” he said.
Tesla’s Autopilot is an advanced driver assistance system that Tesla says "enhances safety and convenience behind the wheel".
The company warns customers that drivers must pay attention and be ready to take control of the vehicle when using the driver-assist system.
However, the National Transportation Safety Board said last year that the design of the system allows drivers to avoid paying attention and fails to limit where Autopilot can be used.
It comes days after two passengers were killed in Texas when a Tesla vehicle veered off-road and crashed into a tree at high speed.
A police officer told television stations in Houston that one of the victims of the crash on Saturday night was in the front passenger seat while the second was on the back seat.
Authorities believe no one was in the driver’s seat.
Harris County precinct Constable Mark Herman said: "They feel very confident just with the positioning of the bodies after the impact that there was no one driving that vehicle."
Tesla CEO Elon Musk said on Twitter on Monday that data logs “recovered so far” show “Autopilot” was not turned on in the Texas crash.
"Moreover, standard Autopilot would require lane lines to turn on, which this street did not have," Mr Musk tweeted.
On Thursday, two Democratic Senators sent a letter to the US National Highway Traffic Safety Administration (NHTSA) requesting them to investigate the fatal Tesla accident.
Senator Blumenthal and Senator Markey also requested a report outlining ways to prevent potential accidents in the future.
Tesla has been approached for comment.