Dip in MPG for winter?

[Jake F]

I’m in south-central Arizona where it doesn’t get too cold. From 80-115ºF weather I was getting around 29 miles to the gallon. Now that it’s 40-70ºF, I’ve been increasingly getting worse–24 mpg. My daily route has changed, but my driving habits and city vs freeway driving has remained relatively unchanged. I’ve been filling my tank at new locations with the same brands as before, and while my car’s still peppy, it isn’t getting those extra miles that I was getting a few months ago. I even filed the tank at a Mobil station last fill for the first time in 10 years and got the worst mileage I’ve gotten in a while. What the hay!?

I thought that the winter blend switch is supposed to be a benefit for our ‘older’ vehicles resulting in better gas mileage. But come to think about it, even at 40 degrees in the morning, my car takes longer to reach operating temperature than if it was warmer out. Could my early morning startup-to-warm-up time really be affecting the mpg efficiency by 92 miles per tank? Or do I have to submit a sample of the gasoline I purchase to someone who can examine the quality? Last 3 fills have been Top-Tiers and frankly, I’m not too thrilled.

Topic

[zero]

Winter mix gasolines are crap in my experience, I drive a car that’s somewhat picky about the gas that goes in it and experience actual winter.

If you’re idling your car for more than a minute, remember you’re getting zero miles per gallon. During cold temperatures your car will run on the rich side to warm up the engine faster.

[Mike]

Colder air is denser than warmer air. To keep the air/fuel ratio correct, you are adding more fuel to the colder air, which is going to eat into your MPG a bit.

[Larry Stock]

Agree, Cold air more fuel and oxygenated winter mixes
what about new route? is it hilly vs previous that kills my mpg inclines. I know Arizona and though it feels flat you drive for an hour and suddenly your at the top of a rim at 6k feet.

[Author]

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