SAN FRANCISCO — A Tesla will operate with no one in the driver’s seat, a leading consumer protection group found, raising new concerns about the electric-vehicle maker’s rollout of driver assistance features.

Consumer Reports found a Tesla Model Y crossover would operate in Autopilot mode without a driver after attaching a weight to the steering wheel to trick a sensor Tesla uses for driver monitoring. Tesla seats also have weight sensors that cars use for seat-belt and air-bag warnings, Consumer Reports noted, but they are not used to block the use of Autopilot if a driver is not present.

The group managed to activate Autopilot without a driver on a closed track and travel at speeds up to 30 mph, it said. Consumer Reports urged people not to repeat the experiment for themselves, citing the extreme danger of doing so on a public road.

“The car drove up and down the half-mile lane of our track, repeatedly, never noting that no one was in the driver’s seat, never noting that there was no one touching the steering wheel, never noting there was no weight on the seat,” said Jake Fisher, the group’s senior director of auto testing, according to the report. “It was a bit frightening when we realized how easy it was to defeat the safeguards, which we proved were clearly insufficient.”

Tesla did not immediately respond to a request for comment about Consumer Reports’ findings.

Tesla’s Autopilot technology has come under increased scrutiny after a Model S sedan veered off the road in a Houston suburb over the weekend, catching fire and killing two people. Harris County Precinct 4 Constable Mark Herman told news outlets that police were certain that no one was in the driver’s seat at the time of the crash.

But Tesla CEO Elon Musk said in a tweet Monday that “so far” data showed Autopilot was not enabled at the time of the crash.

Autopilot is an advanced driver-assistance system that can navigate from highway on-ramp to off-ramp, detect stop signs and traffic lights, and automatically park and summon Tesla vehicles. Drivers still have to pay attention at all times, the company advises, and automakers have different degrees of driver monitoring to ensure their systems are not being abused.

Federal authorities including the National Highway Traffic Safety Administration and National Transportation Safety Board are investigating the crash.