PHEV (sometimes PHV) is the abbreviation for Plug-in Hybrid Electric Vehicle also referred to as plug-in hybrid. A PHEV utilizes rechargeable batteries, or another energy storage device, that can be restored to full charge by connecting a plug to an external electric power source (usually a normal electric wall socket). A PHEV shares the characteristics of both a conventional hybrid electric vehicle, having an electric motor and an internal combustion engine and of an all-electric vehicle, having a plug to connect to the electrical grid. Most PHEVs on the road today are passenger cars, but there are also PHEV versions of commercial vehicles and vans, utility trucks, buses, trains, motorcycles, scooters, and military vehicles.

The cost for electricity to power plug-in hybrids for all-electric operation has been estimated at less than one quarter of the cost of gasoline in California. Compared to conventional vehicles, PHEVs reduce air pollution locally and dependence on petroleum. PHEVs may reduce greenhouse gas emissions that contribute to global warming, compared with conventional vehicles. PHEVs also eliminate the problem of range anxiety associated with all-electric vehicles, because the combustion engine works as a backup when the batteries are depleted, giving PHEVs driving range comparable to other vehicles with gasoline tanks. PHEVs use no fossil fuel at the point of use during their all-electric range.

Greenhouse gas emissions attributable to operation of PHEVs during their all-electric range depend on the type of power plant that is used to meet additional demand on the electrical grid at the time and place where the batteries are charged. If the batteries are charged directly from renewable sources off the electrical grid, then the greenhouse gas emissions are essentially zero.