At least 13 automobile drivers have died due to a faulty ignition-switch in General Motors cars. “I cannot tell you why it took years for a safety defect to be announced. I can tell you that we will find out,” GM chief executive Mary T. Barra told the House Energy and Commerce Committee during a hearing Tuesday. GM let a decade pass before it recalled more than two million Chevrolet Cobalts and other vehicles due to the manufacturing error.