Gasoline and Winter

The cold can affect just about anything in your daily life, including your gasoline. That’s right, winter blend gas is different than summer blend. But it doesn’t end there. How does the cold affect your fuel economy? And did you ever wonder if using your heat and heated seats used up more gasoline? And does heating up your car before driving actually improve efficiency? Let’s take a look!

Winter Vs. Summer Mix

The seasonal gas transition might be something you’re not too familiar with. Simply put, the transition is the changing over from a summer mix to a winter mix during colder months. The Reformulated Gasoline Program began in 1995 to reduce air pollution during the summer because it burns cleaner than winter fuel due to its ingredients. The special ingredients increase the price of summer fuel, so this winter you’re saving an average of 18 cents per gallon as compared to one year ago.

But what exactly is the difference and more importantly, why is there a difference — and is it making any difference?

I’m no Bill Nye, but I’ll try my best to explain the science behind the reason your gasoline changes with the seasons. It all starts with Reid Vapor Pressure (RVP). RVP measures the volatility of gas, and regulating it helps meet the Environmental Protection Agency’s standards for reducing emissions. In the best description, the higher the RVP, the easier it is for gas to evaporate. This is important since low RVP on cold days will cause your engine to have a hard time starting and running. In summer, fuel can’t be pumped so long as there is vapor in the fuel line. Conversely, in winter, you need gasoline to vaporize in the combustion chambers to ensure your engine runs at its peak. Oil refineries tamper with the RVP to help your engine run smoothly, and in winter that means adding butane. Because butane is abundant and less expensive, that’s why you typically see gas prices drop in colder weather.

So to recap, this change in summer/winter-grade gasoline is based mostly on environmental concerns during ozone months. According to the EPA, since 2001, about 75 million Americans are breathing cleaner air due to the Reformulated Gasoline Program. That’s being part of the solution and not part of the pollution!

Fuel Economy in Winter

Most of your daily trips involve shorter distances to and from work, or to pick up the kids from school, or hit your local grocer for the night’s fare. In those short, city trips, gas mileage in the winter can be significantly reduced compared to days where the temperature reaches the high 70s. Typically, vehicles see about a 12% drop in gas mileage at 20 degrees while hybrids suffer even more and drop up to 34% in the same conditions! The cold simply increases friction, making it harder to keep moving effectively. It takes longer for your engine to reach its fuel-efficient temperature, so when you’re taking shorter trips you never even hit that number. Not to mention, in harsher weather, your spinning tires waste energy, reducing fuel economy even more.

Do you know this feeling: You could swear you just filled the tank the other day but you’re getting close to a quarter tank again? It turns out that using the heat, defrosters, heated seats, and heated a steering wheel use more power and that means more gasoline. But winter tires can help you counter some of that with their unmatched traction potential.

Heating Your Car in the Winter

Should you warm up your car up in the winter? A lot of people just want their car to be warm when they get in, but they find themselves at the gas pump a whole lot more during cold months. The best explanation is simple — an idling car gets 0 miles to the gallon. This practice was for a time when carburetors needed those precious minutes to mix air and gas in the engine before heating it up in order to avoid stalling. Today’s fuel-injected engines allow your car to warm up while driving miles instead of idling and going nowhere. Also, if you heat up the car for an extended period, you might be putting extra fuel in the combustion chamber but not actually warming up the engine. Thus, wasting gasoline!

It should be noted that this isn’t a globally accepted theory. Some experts believe that fluids thicken in cold temperatures and since oil is the life-blood of your vehicle, it needs extra time to lubricate the system. For some, that means warming up your car in winter for at least a few seconds, while others believe it takes minutes.

No matter what, it’s your car, your gas, and your call!