The Effect of Cold Temperatures on Fuel Economy

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Winter driving conditions and cold temperatures can have a significant effect on a vehicle’s fuel economy. For a conventional gasoline-powered vehicle, fuel economy at 20°F in city driving is about 15% lower than at 77°F.

The effect of temperature on electrified vehicles is even more pronounced. Hybrid vehicles, which rely on a larger battery, can experience a decrease in fuel economy of around 30%, while all-electric vehicles can experience a decrease in fuel economy of nearly 40% in cold temperatures. Tests were conducted in a controlled laboratory setting. For more information on the effects of winter conditions on fuel economy, visit Fuel Economy in Cold Weather.

Fuel Economy in Cold Weather

Cold weather and winter driving conditions can reduce your fuel economy significantly.

Fuel economy tests show that, in city driving, a conventional gasoline car’s gas mileage is roughly 15% lower at 20°F than it would be at 77°F. It can drop as much as 24% for short (3- to 4-mile) trips.

The effect on hybrids is typically greater. Their fuel economy can drop about 30% to 34% under these conditions.

For electric vehicles (EVs), fuel economy can drop roughly 39% in mixed city and highway driving, and range can drop by 41%. About two-thirds of the extra energy consumed is used to heat the cabin.

Cold weather effects can vary by vehicle model. However, expect conventional gasoline vehicles to suffer a 10% to 20% fuel economy loss in city driving and a 15% to 33% loss on short trips.

For hybrids, fuel economy typically decreases by 20% to 40% in city driving and 25% to 45% on short trips.

When the cabin heater is not used, EV fuel economy is 8% lower at 20°F than at 75°F. Driving range is about 12% lower.

Why is winter fuel economy lower?

Cold weather affects your vehicle in more ways than you might expect:

• Engine and transmission friction increases in cold temperatures due to cold engine oil and other drive-line fluids.
• It takes longer for your engine to reach its most fuel-efficient temperature. This affects shorter trips more, since your car spends more of your trip at less-than-optimal temperatures.
• Heated seats, window defrosters, and heater fans use additional power.
• Warming up your vehicle before you start your trip lowers your fuel economy — idling gets 0 miles per gallon.
• Colder air is denser, increasing aerodynamic drag on your vehicle, especially at highway speeds.
• Tire pressure decreases in colder temperatures, increasing rolling resistance.
• Winter grades of gasoline can have slightly less energy per gallon than summer blends.
• Battery performance decreases in cold weather, making it harder for your alternator to keep your battery charged. This also affects the performance of the regenerative braking system on hybrids, plug-in hybrids, and electric vehicles.

In severe winter weather, your mpg can drop even further.

• Icy or snow-covered roads decrease your tires’ grip on the road, wasting energy.
• Safe driving speeds on slick roads can be much lower than normal, further reducing fuel economy, especially at speeds below 30 to 40 mph.
• Using four-wheel drive uses more fuel.

What can I do to improve my fuel economy in cold weather?

You may not be able to completely mitigate cold weather’s effect on your fuel economy, but you can do some simple things to help your gas mileage:

• Park your car in a warmer place, such as your garage, to increase the initial temperature of your engine and cabin.
• Combine trips when possible so that you drive less often with a cold engine.
• Minimize idling your car to warm it up. Most manufacturers recommend driving off gently after about 30 seconds. The engine will warm up faster being driven, which will allow the heat to turn on sooner, decrease your fuel costs, and reduce emissions.
• Don’t use seat warmers or defrosters more than necessary.
• Check your tire pressure regularly.
• Use the type of oil recommended by your manufacturer for cold weather driving.
• Remove accessories that increase wind resistance, like roof racks, when not in use.
• If you drive a plug-in hybrid or electric vehicle, preheating the cabin while plugged into the charger can extend your vehicle’s range.
• If you drive a plug-in hybrid or electric vehicle, using the seat warmers instead of the cabin heater can save energy and extend range.

Article courtesy of the US Department of Energy — this page and this page combined.