'Extensive' Tesla Autopilot probe proceeding 'really fast', U.S. official saysWASHINGTON, Jan 9 (Reuters) - The acting head of the National Highway Traffic Safety Administration (NHTSA) told reporters on Monday that the regulatory agency is "working really fast" on the Tesla (TSLA.O) Autopilot investigation it opened in August 2021."The resources require a lot of technical expertise, actually some legal novelty and so we're moving as quickly as we can, but we also want to be careful and make sure we have all the information we need."In June, NHTSA upgraded to an engineering analysis its defect probe into 830,000 Tesla vehicles with driver assistance system Autopilot and involving crashes with parked emergency vehicles.Previously, the agency said evidence suggested drivers in most crashes under review had complied with Tesla's alert strategy that seeks to compel driver attention, raising questions about its effectiveness.Tesla sells the $15,000 FSD software as an add-on which enables its vehicles to change lanes and park autonomously."