The U.S. National Highway Traffic Safety Administration said Monday it is expanding a defect investigation of 856,000 Fiat Chrysler SUVs and cars because the vehicles may roll away after drivers exit, thinking they have put the transmission in Park. The government’s investigation covers the 2014-15 Jeep Grand Cherokee SUV, 2012-14 Dodge Charger and Chrysler 300. The vehicles under investigation have “E-shift” gear-shifts that operate electronically.