WASHINGTON — In the sharpest comments of his young tenure as the nation’s top auto safety regulator, Mark R. Rosekind promised on Tuesday to take aggressive action on vehicle recalls that move too slowly and continue to endanger lives.
Mr. Rosekind, who took over as administrator of the National Highway Traffic Safety Administration in December, took particular aim at Fiat Chrysler Automobiles, saying that its efforts to fix more than a million Jeep sport utility vehicles with potentially dangerous gas tanks had fallen far short of expectations.
