Fuel Economy & Efficiency Reference

Units like L/100 km or kWh/100 km measure consumption per distance, so lower values mean less energy used. Units like MPG or km/L measure distance per fuel, so higher values are better.

UK (imperial) gallons are larger. To convert US MPG to UK MPG, multiply by 1.20095. The reverse conversion divides by the same factor.

Include charging efficiency and ambient temperature. Cold weather and high-speed driving reduce mi/kWh even if the rated consumption stays constant.

Roughly: efficient sedans and small crossovers run 14-18 kWh/100km (about 3.7-4.6 mi/kWh), midsize SUVs 18-24 kWh/100km (2.7-3.7 mi/kWh), and larger trucks or SUVs often exceed 24 kWh/100km (under 2.7 mi/kWh). Lower kWh/100km and higher mi/kWh both mean better efficiency.

Cold weather, highway speeds, HVAC use, and battery degradation all increase real-world consumption above the rated (typically mild-weather, moderate-speed) test figure. A 20-30% gap in cold conditions is common.

Divide usable battery capacity (kWh) by consumption per 100 km or 100 mi, then multiply by 100. For example, a 60 kWh battery at 18 kWh/100km gives roughly 333 km of range.

EPA's consumer MPGe label uses a fixed energy-equivalence constant (33,705 Wh per gallon of gasoline) derived from five-cycle dynamometer testing. A separate, unrelated figure — the Petroleum Equivalency Factor, used only for manufacturer fuel-economy compliance credit — is being phased down from 82,049 Wh/gallon toward 28,996 Wh/gallon by model year 2030. The two constants serve different purposes and are often confused.