The investigation applies to 765,000 Model Y, X, S, and 3 electric vehicles made since 2014, the NHTSA said. File Photo by Stephen Shaver/UPI | License Photo
Aug. 16 (UPI) -- Federal regulators have opened an official investigation to look into more than 700,000 Tesla vehicles in the United States -- specifically, the vehicles' self-driving system that's been linked to nearly a dozen crashes involving emergency vehicles like police cars and ambulances.
The National Highway Traffic Safety Administration announced the inquiry, which covers virtually all Tesla vehicles sold in the United States for the past seven years.
The investigation applies to 765,000 Model Y, X, S, and 3 electric vehicles made since 2014.
The inquiry comes after 11 crashes involving the Tesla models and emergency vehicles since 2018, which have resulted in 17 injuries and one death. Four of those crashes happened this year.
The investigation is focused on the models' autonomous driving system, which partly navigates the vehicles without human assistance.
"Most incidents took place after dark and the crash scenes encountered included scene control measures such as first responder vehicle lights, flares, an illuminated arrow board, and road cones," the NHTSA said in a statement.
"The involved subject vehicles were all confirmed to have been engaged in either Autopilot or Traffic Aware Cruise Control during the approach to the crashes."
The agency said the inquiry will "assess the technologies and methods" that Tesla uses to monitor and enforce human drivers' engagement when the autopilot is switched on.
Tesla's autopilot system can handle multiple driving functions, such as steering and braking, but human drivers are still supposed to monitor operation of the vehicle and watch out for potential hazards.
The NHTSA and National Transportation Safety Board have previously looked into Tesla's self-driving system.
The U.S. inquiry could lead to a deeper investigation and, ultimately, a safety recall.