Fuel Economy in Cold Weather
Cold weather and winter driving conditions can reduce your fuel economy significantly.
Fuel economy tests show that, in short-trip city driving, a conventional gasoline car’s gas mileage is about 12% lower at 20°F than it would be at 77°F. It can drop as much as 22% for very short trips (3 to 4 miles).
The effect on hybrids is worse. Their fuel economy can drop about 31% to 34% under these conditions.
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.
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.
Severe weather can be both frightening and dangerous for automobile travel. Motorists should know the safety rules for dealing with winter road emergencies. AAA reminds motorists to be cautious while driving in adverse weather.
AAA recommends the following winter driving tips:
- Avoid driving while you’re fatigued. Getting the proper amount of rest before taking on winter weather tasks reduces driving risks.
- Never warm up a vehicle in an enclosed area, such as a garage.
- Make certain your tires are properly inflated.
- Never mix radial tires with other tire types.
- Keep your gas tank at least half full to avoid gas line freeze-up.
- If possible, avoid using your parking brake in cold, rainy and snowy weather.
- Do not use cruise control when driving on any slippery surface (wet, ice, sand).
- Always look and steer where you want to go.
- Use your seat belt every time you get into your vehicle.
Tips for driving in the snow:
- Accelerate and decelerate slowly. Applying the gas slowly to accelerate is the best method for regaining traction and avoiding skids. Don’t try to get moving in a hurry. And take time to slow down for a stoplight. Remember: It takes longer to slow down on icy roads.
- Drive slowly. Everything takes longer on snow-covered roads. Accelerating, stopping, turning – nothing happens as quickly as on dry pavement. Give yourself time to maneuver by driving slowly.
- The normal dry pavement following distance of three to four seconds should be increased to eight to ten seconds. This increased margin of safety will provide the longer distance needed if you have to stop.
- Know your brakes. Whether you have anti-lock brakes or not, the best way to stop is threshold breaking. Keep the heel of your foot on the floor and use the ball of your foot to apply firm, steady pressure on the brake pedal.
- Don’t stop if you can avoid it. There’s a big difference in the amount of inertia it takes to start moving from a full stop versus how much it takes to get moving while still rolling. If you can slow down enough to keep rolling until a traffic light changes, do it.
- Don’t power up hills. Applying extra gas on snow-covered roads just starts your wheels spinning. Try to get a little inertia going before you reach the hill and let that inertia carry you to the top. As you reach the crest of the hill, reduce your speed and proceed down hill as slowly as possible.
- Don’t stop going up a hill. There’s nothing worse than trying to get moving up a hill on an icy road. Get some inertia going on a flat roadway before you take on the hill.
- Stay home. If you really don’t have to go out, don’t. Even if you can drive well in the snow, not everyone else can. Don’t tempt fate: If you don’t have somewhere you have to be, watch the snow from indoors.
Tips for long-distance winter trips:
- Watch weather reports prior to a long-distance drive or before driving in isolated areas. Delay trips when especially bad weather is expected. If you must leave, let others know your route, destination and estimated time of arrival.
- Always make sure your vehicle is in peak operating condition by having it inspected by an Auto Repair facility.
- Keep at least half a tank of gasoline in your vehicle at all times.
- Pack a cellular telephone with your local towing company’s telephone number, plus blankets, gloves, hats, food, water and any needed medication in your vehicle.
- If you become snow-bound, stay with your vehicle. It provides temporary shelter and makes it easier for rescuers to locate you. Don’t try to walk in a severe storm. It’s easy to lose sight of your vehicle in blowing snow and become lost.
- Don’t over exert yourself if you try to push or dig your vehicle out of the snow.
- Tie a brightly colored cloth to the antenna or place a cloth at the top of a rolled up window to signal distress. At night, keep the dome light on if possible. It only uses a small amount of electricity and will make it easier for rescuers to find you.
- Make sure the exhaust pipe isn’t clogged with snow, ice or mud. A blocked exhaust could cause deadly carbon monoxide gas to leak into the passenger compartment with the engine running.
- Use whatever is available to insulate your body from the cold. This could include floor mats, newspapers or paper maps.
- If possible run the engine and heater just long enough to remove the chill and to conserve gasoline.
Four-wheel drive vehicles, sometimes called 4×4 or all-wheel drive, demand rugged performance, especially when used for off-roading and towing.
And components that have to work extra hard require periodic TLC. Take the transfer case, for example. It helps deliver power from the transmission to the wheels. In four-wheel drive, power from the engine is directed to both the front and rear axles. In all-wheel drive, it shifts power from one axle to the other, depending on conditions. Your transfer case requires lubrication, just like the engine and transmission. It has its own fluid, which should be checked and changed at regular intervals. This is even more important in four-wheel and all-wheel drive vehicles because if the fluid degrades enough, the vehicle might not be able to shift into four-wheel drive.
Similarly, the differential requires regular maintenance. This gear box is located between the drive wheels and allows them to turn at different speeds as the vehicle is taking turns. Over time, the properties of the lubricating fluid inside deteriorate, resulting in improper lubrication of the gears. At Auto Select, we’ll replace the old fluid with fresh fluid, which helps avoid excessive wear on the differential. This is key to saving yourself a costly differential or axle replacement.