Winter Weather Cuts MPGs by One Third: Study


It shouldn’t come as much of a surprise that colder weather hurts fuel economy, but you might be surprised to learn how steep the penalties can be.

Results from new research conducted by Oak Ridge National Laboratory suggests that some vehicles suffer a third hit in mpgs in 20-degree weather. The returns worsen in colder weather and during short trips where the car has less time to warm up.

Conventional gasoline vehicles suffered a roughly 12 percent drop at that temperature compared to “normal” conditions, but cars like the Ford Fusion Hybrid exhibited declines between 31 and 34 percent.

Cold weather is a major contributing factor to decreased mileage, but there are other reasons for cars returning worse fuel economy. Tires slipping on snow and ice will cause them to spin, using more fuel. People tend to let their cars idle longer in cold weather where they get zero miles per gallon and the car’s systems operate less efficiently in cold weather. For example, running seat heaters and fans calls for more energy from the car. Winter fuel blends are also less energy dense. In colder temperatures, your vehilce’s fluids will also cause more internal friction.

But Oak Ridge suggests a handful of steps to improve your winter fuel economy. They suggest using the manufacturer-recommended oil for cold weather use. Spend less time running your car at idle to warm it up. It will reach the optimal operating temperature sooner while driving. It’s also important to be diligent about tire pressure. Tires lose pressure in cold weather and softer tires cause rolling resistance and cost more fuel.