(Adds no Tesla comment (paragraph 2); Adds background and details from letter (paragraphs 4-10))
By David Shepardson
WASHINGTON, July 6 (Reuters) - U.S. auto safety regulators said on Thursday they are seeking updated responses and current data for an ongoing probe into 830,000 Tesla vehicles and the automaker's advanced driver assistance system Autopilot.
The National Highway Traffic Safety Administration (NHTSA) sent Tesla a letter on July 3 seeking updates to questions it had asked in August 2022 and is now demanding answers by July 19, according to a copy of the letter made public by the agency.
Tesla did not respond to a request for comment.
The agency is investigating the performance of Autopilot after identifying more than a dozen crashes in which Tesla vehicles struck stopped emergency vehicles. It is also investigating whether Tesla vehicles adequately ensure drivers are paying attention when using the driver assistance system.
Autopilot is intended to enable cars to steer, accelerate and brake automatically within their lane, while enhanced Autopilot can assist in changing lanes on highways. Tesla's Full Self-Driving Capability Features enables vehicles to obey traffic signals and stop signs but does not make them autonomous.
NHTSA has said evidence had raised questions about the effectiveness of Tesla's alert strategy, which seeks to compel driver attention.
The agency said in 2022 nine of 11 vehicles in prior crashes exhibited no driver engagement, or visual or chime alerts, until the last minute preceding a collision, while four showed no visual or chime alerts at all during the final Autopilot use cycle.
The letter asks for updates on all Tesla changes related to driver engagement or attentiveness.
In June 2022, NHTSA upgraded the probe it first opened in August 2021 to an engineering analysis - a required step before it could potentially demand a recall.
NHTSA previously sought information about cabin camera - a camera located above the rear view mirror - that Tesla says can determine driver inattentiveness and provide audible alerts to remind the driver to keep their eyes on the road when Autopilot is engaged.
The new letter, asks for data on the number of vehicles with "Tesla Vision" - equipped with cameras only and not radar - and if vehicles have the cabin camera system.
Since 2016, NHTSA has opened 40 Tesla special crash investigations where advanced driver assistance systems such as Autopilot were suspected of being used with 20 crash deaths reported.
Transportation Secretary Pete Buttigieg said in May there are real concerns about the interaction between Autopilot and drivers. (Reporting by David Shepardson; Editing by Jason Neely and Conor Humphries)