How cold weather kills your gas mileage (and what to do about it)

There are several reasons your gas mileage goes down during the winter months.
There are several reasons your gas mileage goes down during the winter months. –Alex Brandon / AP

The cold weather still threatens your vehicle’s fuel efficiency, especially when the temperature drops below freezing levels.

According to FuelEconomy.gov, a regular gasoline-powered car sees its gas mileage drop by 12 percent when the temperature is 20 degrees, compared to a more pleasant temperature of 77 degrees. It can lose even more gas mileage (as much as 22 percent) during short trips of three to four miles.

FuelEconomy.gov says hybrid cars have it even worse. Hybrids can lose between 31 to 34 percent of their gas mileage during cold weather conditions.

There are several reasons why a vehicle’s fuel economy falls during the cold weather.

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• A vehicle’s engine may require more time to reach its optimal fuel-efficient temperature. This is why a vehicle performs even worse during shorter trips, because it spends a greater percentage of the trip at a less-than-optimal temperature.

• Cold weather also reduces a vehicle’s tire pressure, which can increase resistance.

• Gas pumps switch to winter grades of gasoline, which have slightly less energy per gallon than summer gas blends.

• A car’s warming features, including defrosters, fans, and heated seats, can draw more power from the car.

• Cold air is denser than warm air and puts more of an aerodynamic drag on the vehicle, especially when travelling at highway speeds.

A vehicle’s fuel economy will only get worse during severe weather. Icy and slippery roads can cause a vehicle to lose its grip on the road, forcing it to spend more energy to move the same distance. In addition, drivers also tend to drive much slower on icy roads, and fuel economy is worse at speeds below 30 to 40 mph.

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So what can you do?

As FuelEconomy.gov puts it, “you may not be able to completely mitigate cold weather’s effect on your fuel economy.’’ But there are some simple steps you can take to protect your gas mileage.

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• Park in a warm space, like a garage, to help boost your vehicle’s enginge initial temperature.

• In order to reduce the amount of time you drive with a cold engine, maximize efficiency by combining as many trips as possible.

• Let your car idle for 30 seconds, not longer. The engine warms up faster while it’s being driven.

• Don’t use your vehicle’s heated seats or defrosters more than necessary.

• If not needed, remove items that contribute to wind resistance, such as a roof rack.

Motorists who have plug-in hybrids or battery electric vehicles should pre-heat their cabins while plugged into the charger and use their seat warmers instead of heaters to boost their vehicle’s range and save energy.

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