Efficiency is the figure almost nobody shops on and the one that changes the most. It sets what you pay per kilometre for the life of the car, and it decides how much battery the manufacturer had to fit to reach a given range — which sets the weight, the price and the replacement cost too.
Ranked from the 18 cars in our database that have a sourced figure for this. A car with no published figure is left out rather than ranked as a zero. Figures are US units; every model page carries the metric equivalent and the source.Figures are metric; every model page carries the imperial equivalent and the source.
Why efficiency beats capacity
The pattern repeats right through our database: the car with the bigger battery often goes less far. The Nissan Ariya carries 87 kWh usable and returns about 402 km observed. The Tesla Model 3 carries 79 kWh and returns about 555 km. Eight kilowatt-hours less battery, a hundred and fifty kilometres more range — because one uses 216 Wh/km and the other 142.
That 74 Wh/km gap is about 1,100 kWh a year at 15,000 km. At any tariff you like, that is real money, every year, forever. Put your own numbers into the running cost calculator to see it in your currency.
What makes a car efficient
Above roughly 80 km/h, aerodynamic drag dominates, and drag scales with frontal area. That is why the saloons in this table beat the SUVs so consistently, and why two cars sharing a platform can differ by 20 percent: the Hyundai Ioniq 6 returns 149 Wh/km and the Ioniq 5, with the same running gear in a taller body, returns 178.
Weight matters more in town, where you are accelerating and braking rather than pushing air. Neither factor is something a buyer can change after the fact.
Reading the units
This table is in watt-hours per kilometre, where lower is better. The US convention is kWh per 100 miles, also lower-is-better, and every car page on this site shows both. Miles per kWh appears occasionally and inverts the direction — higher is better — which is a reliable way to compare two numbers that are not comparable, so we avoid it.
One note on the source: these are EV Database’s real-world consumption estimates, not the WLTP laboratory figure. That is why dividing usable capacity by the number in this column returns the observed range on each car’s page — the two are the same measurement seen from different ends. They are estimates rather than measurements, so treat a gap of two or three Wh/km between neighbouring cars as noise.
The rankings on this site cover the cars we document in full. If you want the whole US market instead — every electric car the EPA has certified, 403 models, searchable and sortable — that is the electric car range comparison. It is EPA range and consumption only, and it says so.
Frequently asked questions
Is a lower Wh/km always better?
For cost and range, yes. But efficiency is largely bought with a low, narrow body, so the most efficient cars in this table are also the least practical for carrying people and things. That is a genuine trade, not a flaw in the metric.
How much does 20 Wh/km actually cost me?
At 15,000 km a year, 20 Wh/km is 300 kWh. Multiply by your tariff. It is not a large number in a single year and it is a substantial one across the time most people keep a car.
Why do the figures here differ from my car’s display?
Because a dashboard readout is your driving, your route and your weather, and these are a standard cycle. Expect your own figure to be higher. The value of a standard test is not that it predicts your consumption; it is that it compares cars on the same terms.