How's Your Gas Mileage This Winter?

Winter blend gasoline, which kicked in early this year, can lower a car's mileage. What's it doing for yours?

About a month ago, I noticed something terrible. As gas prices were going up, my mileage was plummeting.

It dropped from 25 miles a gallon to 17 (no hybrid here), enough to make me consider joining the modern age and getting rid of my 20-year-old car.

First, however, I tried everything I could to up the efficiency. I replaced the tires and spark plugs. I got it tuned up. But, no luck. The needle in the gas tank was dropping like the altimeter on a falling plane. 

So, I hit up my mechanical buddy, George Loughran, who had the answer right away.

"Five miles a gallon? That's the winter blend."

Oh yeah, the gas we Californians put in our cars from November through March, is dirtier and contains additives such as butane, which burn at a higher vapor pressure. They make the gas cheaper, but far less efficient than the more pure summer gas, which burns at a much lower pressure and is more pure.

Butane, for example, would boil off as a gas in summer, but can help fill a tank in the winter.

The summer and winter switch isn't much thought about, but became an issue in October when Gov. Jerry Brown asked the Air Resources Board to allow the winter gas to be sold before Oct. 31, because gas prices were reaching record highs.

So, we get cheaper gas, but have to use more of it? I'm not sure how the math works here.

How is it working in your tank? Are you Prius and Volt owners feeling smug in the smog?

Should I take the plunge and get something more fuel efficient, as opposed to a car with no payments?

P.S.: California gas prices averaged just over $4 a gallon in 2012, a record, beating last year's high of $3.50 a gallon. Nationwide prices averaged $3.60 a gallon, according to this story in the Los Angeles Times.

Let us know how the winter formula is affecting your mileage.

Bob Henry January 06, 2013 at 05:07 PM
Well,I feel a "little" better now with this info; thought i had worn out my engine when I noticed my pickup's performance drop! Just more help from our goverment; business as usual. The voters showed what they wanted so now enjoy!
JY January 06, 2013 at 08:45 PM
Three points. In the past I was under the impression that Winter gas was higher quality and produced more energy in cold weather. Secondly, do the car manufactures use the highest quality seasonal gasoline when determining EPA Mileage Ratings? Finally, I believe gasoline taxes are determined as a rate per gallon verses price per gallon leading many taxing bodies to complain about improved mileage and to research possible " miles driven" as the basis of highway taxes.
Casey January 07, 2013 at 01:51 AM
I drive a prius and have been lucky to get 37mpg the past few months, and I'm a conservative driver. During the summer I was getting an average of 42mpg. This is a car that's advertised to get between 45-50mpg. Something is terribly wrong here.
Voter with an ID January 07, 2013 at 04:40 PM
You've stumbled upon one of the states lesser known methods of increasing tax revenue by forcing drivers to purchase more gas. Although I'm sure this situation really tees off those wacky anti-oil zealots who realize this winter change brings in more revenue for the oil comapnies, as well.
kevin January 07, 2013 at 08:07 PM
I've also noticed a huge increase in the number of check engine lights that come on with a code stating the catalytic converter efficiency has dropped off. The code comes up on every type of vehicle and all have started about the same time. There is no problem with the converter passing a smog test. I think the increase in alcohols is causing the rear oxygen sensor to fluctuate and the computer is interpreting this as a bad converter. If you have a catalytic converter code beware it might not in fact be the converter.


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