The National Highway Traffic Safety Administration closed a long-standing investigation into Tesla’s Autopilot driver assistance system after reviewing hundreds of crashes involving its misuse, including 13 that were fatal and “many more involving serious injuries.” At the same time, NHTSA is opening a new investigation to evaluate whether the Autopilot recall fix that Tesla implemented in December is effective enough. NHTSA’s Office of Defects Investigation said in documents released Friday tha...