If your fuel economy seems to slip every winter, you’re not imagining it. In cold weather, a typical gas car gets noticeably fewer miles per gallon in city driving, and short trips can be hit much harder. The drop is normal, mostly temporary, and partly in your control. Here’s what causes it and what you can do about it.
How big is the winter drop?
According to the U.S. Department of Energy, a conventional gas car’s fuel economy in city driving is roughly 15% lower at 20°F than at 77°F, and it can fall by as much as 24% on short trips of three to four miles. Hybrids are often hit harder, and electric vehicles lose range too. On the highway the effect is usually smaller, because the engine reaches its working temperature and stays there.
Why cold weather costs you fuel
A cold engine runs rich
Until it warms up, an engine burns extra fuel to run smoothly. The colder it is outside, the longer that takes, and on a short trip you may never reach full operating temperature at all.
Thicker oil and fluids
Cold motor oil, transmission fluid and wheel-bearing grease are thicker, so the engine and drivetrain have to work harder to turn everything over until they warm up.
Denser air and more drag
Cold air is denser than warm air, so the car pushes through more of it. Wind, slush and snow on the road add resistance of their own.
Lower tire pressure
Tire pressure drops as the temperature falls, by roughly 1 psi for every 10°F. Tires that were fine in September can be under-inflated by December, adding rolling resistance.
Winter-blend gasoline
Many areas switch to a winter fuel blend that starts more easily in the cold but holds slightly less energy per gallon than the summer blend.
Heaters, defrosters and seat warmers
Heated seats, rear defrosters and blower fans all put load on the electrical system, which the engine pays for. In hybrids, keeping the cabin warm can also keep the gas engine running more often.
7 ways to win some of it back
1. Skip the long idle warm-up
Modern engines don’t need several minutes of idling. About 30 seconds is enough before you drive off gently, and driving warms the engine faster than idling does. Idling only burns fuel at zero miles per gallon.
2. Combine short trips
Because the first few miles are the least efficient, one loop of errands while the engine is warm beats several cold starts spread across the day.
3. Park somewhere warmer
A garage, even an unheated one, keeps the engine a little warmer and shortens the warm-up. If you have a block heater, plugging it in for a couple of hours before you leave can help in very cold climates.
4. Check tire pressure every few weeks
Check when the tires are cold and top them up to the pressure on the sticker inside the driver’s door. It’s the cheapest efficiency fix there is, and it helps grip on winter roads too.
5. Clear off snow and ice
Snow on the roof and hood adds weight and drag, and it’s a hazard to the drivers behind you. Take off roof racks and cargo boxes you aren’t using.
6. Use the right oil
Use the oil viscosity your owner’s manual recommends for cold weather. Many manuals list a thinner winter grade that flows better on cold starts.
7. Use accessories wisely
Heated seats and a heated steering wheel warm you up using less energy than heating the whole cabin. Turn off the rear defroster once the window is clear.
Know your winter baseline
The best way to tell a normal seasonal dip from a real problem is to track your fuel economy across the year. If your MPG falls about the same amount every winter and recovers in spring, that’s the weather. If it keeps falling, or drops sharply in warm weather, that’s worth a look. The fill-to-fill method gives you an accurate number in about thirty seconds per fill-up, and the habits in How to Lower Your Gas Costs help in any season.
Track the seasons with GasMetrics
We built GasMetrics for iPhone and iPad to make that kind of tracking effortless:
- Log at the pump in seconds. Enter any two of distance, fuel and cost, and GasMetrics works out the third.
- See the winter dip for yourself. Trend charts show how your real MPG and cost per mile change from month to month, so a seasonal drop is easy to tell apart from a sudden problem.
- Compare with the EPA rating. Pick your vehicle and see how your real-world numbers stack up against its official fuel economy.
- Private by design. There’s no account, and your fill-ups stay on your device.
GasMetrics is free to download and tracks one vehicle, with small banner ads. Premium ($4.99 a month or $39.99 a year) removes the ads and adds unlimited vehicles, full history and side-by-side comparisons.
Download GasMetrics on the App Store
Frequently asked questions
Why does my car get worse gas mileage in winter?
Cold engines burn extra fuel while they warm up, oil and fluids are thicker, tire pressure drops, the air is denser, and many areas sell a winter fuel blend with slightly less energy. Short trips feel the effect the most.
How much does gas mileage drop in cold weather?
For a typical gas car in city driving, about 15% at 20°F compared with 77°F, and up to about 24% on short trips, according to the U.S. Department of Energy. Highway driving is usually affected less.
Should I warm up my car before driving in winter?
Not for long. About 30 seconds of idling is enough for most modern cars; after that, driving gently warms the engine faster and wastes less fuel than idling.
Try GasMetrics. Built by Atkinson Interactive. Learn more about GasMetrics →
Download on the App Store