Tesla has until Dec. 18 to respond to NHTSA's letter, which also included requests for extensive information about the company's cars and FSD-related technology. A failure to respond could result in a maximum of $135.8 million in penalties. The company can also ask for an extension.

The NHTSA is investigating possible safety defects in Tesla's FSD option, a partially automated driving system. The latest probe followed a series of Tesla collisions that involved the use of FSD within 30 seconds of impact. In one instance, a Tesla driver using FSD fatally struck a pedestrian.