The National Highway Traffic Safety Administration (NHTSA) said it was opening an investigation after the agency identified concerns due to crash events after vehicles had the recall software update installed "and results from preliminary NHTSA tests of remedied vehicles." The agency's new probe comes after it closed its nearly three-year investigation into Autopilot, saying it found evidence that "Tesla's weak driver engagement system was not appropriate for Autopilot's permissive operating capabilities" that result in a "critical safety gap."