As used in this chapter, unless the context requires a different meaning: “Alternative fuel vehicle” means a vehicle equipped to be powered by a combustible gas, liquid, or other source of energy that can be used to generate power to operate a highway vehicle and that is neither a motor fuel nor electricity used to recharge an electric motor vehicle or a hybrid electric motor vehicle. “Electric motor vehicle” means a vehicle that uses electricity as its only source of motive power. “Fuel-efficient vehicle” means a vehicle that has a combined fuel economy of 25 miles per gallon or greater.