The National Highway Traffic Safety Administration (NHTSA) in June upgraded its probe opened in 2021 to assess the performance of Autopilot after earlier identifying a dozen crashes in which Tesla vehicles struck stopped emergency vehicles.

NHTSA's nine-page letter demands Tesla answer questions by Oct. 12 about "the role that the Cabin Camera plays in the enforcement of driver engagement/attentiveness."

According to Tesla, the cabin camera can determine driver inattentiveness and provide audible alerts to remind the driver to keep their eyes on the road when Autopilot is engaged.

(Reporting by David Shepardson and Hyunjoo Jin, Editing by Rosalba O'Brien)