More than 750 Tesla owners have complained to US safety regulators that vehicles equipped with the automaker's semi autonomous driving systems have abruptly halted on highways for no apparent reason.
The statistic was revealed by the National Highway Traffic Safety Administration (NHTSA) in a comprehensive information request letter to Tesla, which was released on the agency's website on Friday.
The 14-page letter, dated May 4, requests that the carmaker provide all customer and field complaints of false braking, as well as details of collisions, injuries, deaths, and property damage claims.
It also inquires whether the company's "Full Self Driving" and automated emergency braking systems were on at the time of any event.
After receiving 354 complaints, the agency began looking into phantom brakes in Tesla's Models 3 and Y in February. The investigation is expected to involve 416,000 automobiles from the model years 2021 and 2022. The agency stated in February that it had received no reports of collisions or injuries.
The letter gives Tesla until June 20 to answer to the information request, but states that the corporation can request an extension.
A message was sent with Tesla early Friday requesting comment.
The agency said in launching the investigation that it was looking at vehicles with automated driver-assist technologies like adaptive cruise control and "Autopilot," which allows them to automatically brake and steer within their lanes.
“Complainants report that the rapid deceleration can occur without warning, and often repeatedly during a single drive cycle,” the agency said.
Many owners expressed concern about a rear-end crash on a freeway in their comments.
The NHTSA requests the initial speed of when the vehicles began to brake, the final speed, and the average deceleration in the letter. It also inquires whether Tesla has footage of the brake occurrences and whether the automatic systems spotted a target obstruction.
The government is now looking for information on warranty claims for phantom braking, including the identities of the owners and what repairs were performed. It also wants to know about Tesla's sensors, any testing or investigations into the braking issues, and whether any improvements were done.
The letter focuses on Tesla's testing of automated systems to identify metal bridges, s-shaped bends, approaching and cross traffic, and various vehicle sizes, including huge trucks. The government also wants to know how cameras deal with reflections, shadows, glare, and obstructions caused by snow or severe rain.
The agency requests that Tesla provide details on its assessment of the "alleged flaw" in the automated systems, such as what caused the needless braking, what failed, and the danger to motor vehicle safety that the problem creates.
It asks Tesla “what warnings, if any, the operator and the other persons both inside and outside the vehicle would have that the alleged defect was occurring, or subject component was malfunctioning.”
The investigation is part of the agency's ongoing enforcement activities, which include cover Autopilot and "Full Self-Driving" software. Despite their labels, neither feature is capable of driving the cars without human supervision.
It is the Texas automaker's fourth official probe in the last three years, and the NHTSA has overseen 23 Tesla recalls since January 2021.