The U.S. government’s highway safety agency wants detailed information on how Tesla’s Autopilot system detects and responds to emergency vehicles parked on highways.The National Highway Traffic Safety Administration made the request in an 11-page letter sent to the electric car maker that was dated Tuesday.The letter is part of a wide-ranging investigation into how the company’s partially automated driving system behaves when first responder vehicles are parked while crews deal with crashes or other hazards. The agency wants to know how Teslas detect a crash scene, including flashing lights, road flares, reflectorized vests worn by responders and vehicles parked on the road.

NHTSA also wants to know how the system responds to low light conditions, what actions it takes if emergency vehicles are present, and how it warns drivers.The agency also added a 12th crash to its probe in which a Tesla on Autopilot hit a parked Florida Highway Patrol cruiser Saturday on an interstate highway near downtown Orlando. In all the crashes, at least 17 people were injured and one was killed.NHTSA announced the investigation into Tesla’s driver assist systems after a series of collisions with emergency vehicles since 2018. The probe covers 765,000 vehicles from the 2014 through 2021 model years.Autopilot has frequently been misused by Tesla drivers, who have been caught driving drunk or even riding in the back seat while a car rolled down a California highway.The agency also is asking Tesla for all consumer complaints, lawsuits and arbitration cases involving Autopilot. And it wants to know where the system can operate and how it makes sure drivers are paying attention.NHTSA also wants to know Tesla’s policies and procedures for testing Autopilot and updates before they are released to the owners. The request includes “the extent of field testing or vehicle validation miles required prior to the release of such a system or feature.”Tesla “beta” tests its systems using its customers to gather data while they’re driving in traffic.The probe is another sign that NHTSA under President Joe Biden is taking a tougher stance on automated vehicle safety than under previous administrations. Previously the agency was reluctant to regulate the new technology for fear of hampering adoption of the potentially life-saving systems.The National Transportation Safety Board, which also has investigated some of the Tesla crashes dating to 2016, has recommended that NHTSA and Tesla limit Autopilot’s use to areas where it can safely operate. The NTSB also recommended that NHTSA require Tesla to have a better system to make sure drivers are paying attention. NHTSA has not taken action on any of the recommendations. The NTSB has no enforcement powers and can only make recommendations to other federal agencies.Tesla has to respond by Oct. 22 or seek an extension. The agency says it can fine Tesla more than $114 million if it fails to comply.A message was left early Wednesday seeking comment from Tesla, which has disbanded its media relations office.