The fuel economy of gasoline vehicles will increase to meet 2025 corporate average fuel economy standards(CAFE). However, dedicated compressed natural gas(CNG) and battery electric vehicles (BEV) already exceed future CAFE fuel economy targets because only 15% of non-petroleum energy use is accounted for when determining compliance. This study aims to inform stakeholders about the potential impact of CAFE on life cycle greenhouse gas(GHG) emissions, should non-petroleum fuel vehicles displace increasingly fuel efficient petroleum vehicles.