Cold Car Facts: Your Fuel Mileage Will Drop With Winter Weather
Oil prices continue to fall and analysts say gasoline will be cheap for the rest of 2015. Low gas prices are a gift to consumers who find themselves with a little more cash to spend on items more rewarding than feeding their gas tank.
Winter is here, so it helps to know that your actual fuel economy is going to go down in cold weather conditions. There really isn't any way around this, but it helps to understand why you are getting lower gas economy mileage and what measures you can take to look after your car and its engine.
The Environmental Protection Agency tells us what we can do to protect our vehicles in winter weather. Some of this advice is common sense; some is counterintuitive.
The EPA/Department of Energy's Oak Ridge National Laboratory compared the EPA Federal Test Procedure results for 600 conventional fuel vehicles and 14 hybrids under normal temperatures (around 77 degrees Fahrenheit) and cold-weather conditions (20 degrees). In short-trip city driving, a conventional gasoline car's mileage decreases by about 12 percent compared to normal temperatures and it can drop by as much as 22 percent for very short trips of three to four miles. Hybrid fuel economy can drop by 31 to 34 percent under winter conditions. There are many reasons why this happens:
More friction occurs in the engine and transmission because the engine oil and transmission fluids are cold. It takes longer for your engine to warm up and reach its optimum fuel-efficient temperature. On very short trips, your car spends more time at the less-efficient temperature.
The conveniences in your vehicle take power. Heated seats and defrosters use up energy. Remote start is great, but idling lowers fuel economy. Four-wheel drive consumes more gas.
Winter grades of gasoline may have less energy per gallon than summer blends. Tire pressure decreases in the cold, and that increases rolling resistance. And icy or snow-covered roads decrease a tire's grip on the road and can allow more tire spin, which consumes 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.
The batteries that help power hybrids don't perform well in the cold. That makes it hard for the alternator to keep the battery charged and it also affects the performance of the regenerative braking system on hybrids.
Here are a few things you can do to increase fuel economy.
-- Check your tire pressure regularly.
-- Remove accessories that increase wind resistance, like roof racks.
-- Use the type of oil recommended by your manufacturer for cold weather driving.
-- Don't use seat warmers or defrosters more than necessary.
-- Don't idle your car to warm it up. Most manufacturers recommend driving off gently after about 30 seconds. The engine will warm up faster being driven.
-- If you have the option, then 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.
If you drive a plug-in hybrid or electric vehicle, then preheat the cabin while plugged into the charger to extend a vehicle's range. Use the seat warmers instead of the cabin heater to save energy and extend range.
Soon enough the frigid temperatures will turn warmer. But, for now you may try to empathize with your car sitting out in the cold, cold winter.
Lead Photo Credit: The new Land Rover Discovery Sport in the snow-covered region of Iceland.
Kate has written for magazines and newspapers for over 20 years. She has written for More, Edmunds.com, ForbesAutos.com, Houston Chronicle, Motion, Chief Executive, The New York Daily News, The New York Sun, and Autobytel.com. Her column, GirlDriver, USA is syndicated in seven newspapers in Upstate New York. Ms. McLeod is the author of Beetlemania, The Car That Captured the Hearts of Millions. She holds an MFA from Catholic University in Washington, D.C. and is also a playwright. She is former First Vice President of the International Motor Press Association and a member of both The Authors and Dramatists Guilds.