All-electric range (AER) is the driving range of a vehicle using only power from its electric
battery pack to traverse a given driving cycle. In the case of a
battery electric vehicle, it means the total range per charge. For a
plug-in hybrid (PHEV), it means the range of the vehicle in
charge-depleting mode. PHEVs can travel considerably further in
charge-sustaining mode which uses both on-board fuel and the battery pack.