There's no mystery why gas mileage is not as good in the winter, but there are some things you can do to make it better.
Cold weather can be a nuisance; it is cold for one, uncomfortable at times, hard to drive in (when it is snowing), and puts added strain on your vehicle. There is no mystery really as to why your gas mileage is not quite as good in the winter time, but there are a few things that you can do about it.
Poor Alternator/Battery Performance
Cold weather wreaks havoc on a battery and alternator, making them work extra harder to maintain a steady charge in your electrical system. This is why it is important to make sure that you have a healthy battery at the beginning of every winter season. You can get your battery checked for free at just about any automotive store or automotive dealer.
Many people in frigid snowy conditions use added weight to give them better traction (such as the use of sand bags). These items can be removed during good weather when you are certain that they will not be needed. Don't forget about that mound of snow on your roof top or in your truck bed after a hard snow. Take the time to brush off that excess weight rather than drag it around with you all day.
Winter time is generally the start of seeing skis on top of roof racks. Yes, it is great to always be ready to take on a slope, but if you're not going until the weekend, there is no need to leave your skis on your car all week long until then. You're only reducing your vehicles aerodynamics by doing this. This is then compiled by the fact that cold ambient temperatures also make the air thicker and harder to break through.
Low Tire Pressure
For every 5 degrees Celsius the temperature drops, the pressure in a tire will drop by one pound per square foot. Your overall fuel efficiency can be affected by being off as little as 3 lbs on your tire pressure, but more noticeably around 10 lbs or more. Make sure to check your tires periodically as the weather chills to compensate for this slow loss of air pressure.
Winter is the time of more accidents and unless you are driving an electric or hybrid vehicle with regenerative brakes (which actually seem to like stop and go traffic), you are reducing your mileage every time you get into a traffic jam. Make it a habit to check the traffic report before you go anywhere. This will help you to decide on the best route when a traffic hold up is blocking your normal route.
Winter tires are notorious for losing mpg as their tread patterns often create more resistance to the road that summer and all-season tires. But not all winter tires are created equal. There are models available that present much less drag in comparison to others. Green Seal put together a report a few years ago on low resistant tires, which may help guide you on your decision for a new set of winter tread.
It is common for people to let their cars idle longer in cold weather to warm up the engine, and clean frost and ice from their windows. Windows can be easily scraped cold, and most new vehicles do not require idling in the winter to warm up, they can be driven right away and warm up on the way to where you are going.
This updated article was originally published in 2008.