6QQ costs defray EVs CNG fully E85 USQd0Qp10 PHEVs fuel gasoline understocked amortize gallon kWh mileage USQd5000 cheapest cents vehicles price diesel amortized 34Qp95 electric propellant Avcon NiMH GGE ZX40S KELA PHEV LPG overruns powertrain monolights