The short answer
An electric car uses about a quarter of the energy a gas car does to drive the same distance.
Two similar-size SUVs, the same 100 miles, EPA ratings for both:
| 100 miles | Energy used |
|---|---|
| 2024 Toyota RAV4 AWD (gas, 28 mpg) | 3.6 gallons = 120 kWh |
| 2024 Tesla Model Y Long Range (electric) | 29 kWh |
A gallon of gasoline holds the energy of 33.7 kWh. That's the EPA's own conversion, the one behind every "MPGe" on a window sticker. 100 miles ÷ 28 mpg = 3.57 gallons, × 33.7 = 120 kWh.
The electric figure includes what is lost while charging.
Why the gap is so big
Most of a gas engine's energy never moves the car. It leaves as heat.
- Gas cars: about 12% to 30% of the energy in the fuel reaches the wheels.
- Electric cars: over 77% of the electricity from the grid reaches the wheels.
Source: the U.S. Department of Energy and EPA, fueleconomy.gov.
What charging adds at home
Miles × your car's kWh per mile. At 0.29 kWh a mile:
| Miles a day | Charging a day |
|---|---|
| 20 | 5.8 kWh |
| 30 | 8.7 kWh |
| 50 | 14.5 kWh |
Your own car's rating is on fueleconomy.gov, listed as kWh per 100 miles.
On a solar home, that is energy your panels can make in the daytime instead of gasoline you buy.
See your car apart from your house
Charging a car can look like your home suddenly using much more. Link your charger, and WattHacker shows home use and EV charging separately, day by day.
- Works today with an Emporia EV charger, or a Tesla Wall Connector on a home with a Powerwall.
- See what the car took each day, next to what your solar made.
- The monitor is $50 once, with a 30-day money-back guarantee.
Still have questions about your own system? I'll go through it with you — your panels, your bill, and what's worth doing about it.
Book an energy reviewAre your panels installed by SunPower or Enphase? See how it works for SunPower or Enphase, or see a demo.
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Common questions
How many kWh does an electric car use per mile?
It depends on the car; each one is rated in kWh per 100 miles on fueleconomy.gov. The EPA rates a 2024 Tesla Model Y Long Range at 28.7 kWh per 100 miles, which is 0.29 kWh per mile, and that figure includes the energy lost while charging.
How does that compare with a gas car?
A gallon of gasoline holds the energy of 33.7 kWh, the figure the EPA uses for MPGe. A 2024 Toyota RAV4 AWD gets 28 mpg, so 100 miles takes about 3.6 gallons: the energy of about 120 kWh. The electric SUV does the same 100 miles on about 29 kWh, roughly a quarter.
Why do electric cars use so much less energy?
Far less of it is lost as heat. The EPA says electric cars turn over 77% of the electricity from the grid into power at the wheels, while gas cars turn only about 12% to 30% of the energy in gasoline into motion. Most of the rest leaves a gas engine as heat.
How much will charging add to my home's electricity use?
Multiply your miles by your car's kWh per mile. At 0.29 kWh per mile, 30 miles a day is about 8.7 kWh a day. Your car's own rating is on fueleconomy.gov, listed as kWh per 100 miles.
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