evidence: Electric and hybrid vehicles can have significant emissions benefits over conventional vehicles. All-electric vehicles produce zero tailpipe emissions, and PHEVs produce no tailpipe emissions when operating in all-electric mode. HEV emissions benefits vary by vehicle model and type of hybrid power system. The life cycle emissions of an electric vehicle depend on the source of the electricity used to charge it, which varies by region. In geographic areas that use relatively low-polluting energy sources for electricity production, electric vehicles typically have a life cycle emissions advantage over similar conventional vehicles running on gasoline or diesel. In regions that depend heavily on conventional electricity generation, electric vehicles may not demonstrate a strong life cycle emissions benefit. Use the Electricity Sources and Emissions Tool to compare fuel-cycle emissions by vehicle type and state.