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Why gas mileage drops in winter, and what helps
Worse winter mileage is not your imagination. Cold oil, short trips, denser air, lower tire pressure, and winter fuel blends all add up, and electric cars feel it most, because their cabin heat comes from the battery.
Price a winter trip in fuelHow much mileage falls
At 20°F, compared with about 75°F to 77°F.
| Vehicle | Loss at 20°F |
|---|---|
| Gasoline car, city driving | About 15% (10%–20% depending on the model) |
| Gasoline car, 3- to 4-mile trips | Up to 24% (15%–33% depending on the model) |
| Hybrid, city driving | About 30%–34% (20%–40% depending on the model) |
| Electric vehicle, cabin heater on | About 39% of efficiency and 41% of range |
| Electric vehicle, heater off | About 8% of efficiency and 12% of range |
Fueleconomy.gov bases the gasoline and hybrid figures on Oak Ridge National Laboratory analysis of EPA test results, and the electric vehicle figures on a 2019 AAA study.
Where the energy goes
Most of it is lost on short trips.
- Cold fluids: engine oil and other drive-line fluids are thicker in the cold, so friction rises.
- Warm-up time: the engine takes longer to reach its most efficient temperature, which hurts short trips most.
- Heat and defrost: heated seats, window defrosters, and heater fans use extra power.
- Denser air: cold air increases aerodynamic drag, especially at highway speed.
- Tire pressure: pressure drops in the cold, raising rolling resistance.
- Winter fuel: winter gasoline blends can carry slightly less energy per gallon than summer blends.
Batteries also perform worse in the cold, which limits regenerative braking in hybrids and electric cars. Snow, ice, lower safe speeds, and four-wheel drive cost more again.
Don’t idle to warm up
About 30 seconds, then drive off gently.
Warming the car up by idling lowers fuel economy — an idling engine gets zero miles per gallon. Fueleconomy.gov notes that most manufacturers recommend driving off gently after about 30 seconds: the engine warms up faster while driving, which also brings the heat on sooner.
What helps
Habits from the government’s fuel economy site.
- Park in a warmer place, such as a garage, so the engine and cabin start warmer.
- Combine errands into one trip, so you drive less often with a cold engine.
- Use seat warmers and defrosters only as much as you need.
- Check tire pressure regularly; see which PSI is right.
- Use the oil your manufacturer recommends for cold-weather driving.
- Take roof racks off when you are not using them.
The everyday habits in how to improve gas mileage still apply.
Electric cars: heat is the cost
Preheat while plugged in, and prefer seat heaters.
About two-thirds of the extra energy an electric car uses at 20°F goes to heating the cabin. Fueleconomy.gov’s advice for electric cars and plug-in hybrids: preheat the cabin while the car is still plugged into the charger, which can extend range, and use the seat warmers instead of the cabin heater to save energy. To put a price on the extra kilowatt-hours, see the cost to charge at home.
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QUESTIONS THIS ANSWERS
Questions this answers
Why does gas mileage drop in winter?
Cold engine oil and fluids add friction, engines take longer to reach their efficient temperature, heaters and defrosters use power, cold air adds drag, tire pressure falls, and winter gasoline blends can carry slightly less energy.
How much range does an EV lose in cold weather?
Fueleconomy.gov, citing a 2019 AAA study, says that at 20°F an EV’s efficiency can drop roughly 39% and its range 41% with the cabin heater on; without the heater, efficiency was about 8% lower.
Should I warm up my car before driving in winter?
Idling to warm up lowers fuel economy. Fueleconomy.gov notes most manufacturers recommend driving off gently after about 30 seconds, because the engine warms up faster while driving.