Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Winter Fuel Economy

On every car I've ever owned, my fuel economy drops sharply by about 4 MPG around October/November and it jumps back up around March/April. Does anyone know what causes this?

Winter Blend Fuel?

I've always heard that. But why mix gasoline different in winter? There are warm days in winter, cold days in winter, and in-between days in winter. Moreover... modern cars have things like MAF sensors, IAT sensors, and O2 sensors that are supposed to let the car automatically adjust to changes in air density with extreme precision. It makes no sense to me...

I have always had the same problem. I was getting between 250 and 300 milers per tank of gas in the summer. Now I'm getting like 200 - 240. *shrug* It has to be something.

I know here in NM and up in CO they start putting alcohol in the gas. I noticed a considerable drop in mpg (3-4mpg) these past two tanks as well.

They call it reformulated gas or oxygenated fuel. Most metropolitan areas with pollution problems are required to use it in the winter months. If I remember correctly, it is formulated to let off less CO because the atmosphere can't absorb it as well. For some reason, it doesn't burn as easily so your gas mileage drops. Check out this link for more info. I know my gas mileage dropped by 4 points in early november, as it always does. If you live in a rural area, I think they don't have this gas so you wouldn't notice the drop.

Steven
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'98.5 Silver Frost SVT with winter gas mileage

Originally posted by ssolomo:

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They call it reformulated gas or oxygenated fuel. Most metropolitan areas with pollution problems are required to use it in the winter months. If I remember correctly, it is formulated to let off less CO because the atmosphere can't absorb it as well. For some reason, it doesn't burn as easily so your gas mileage drops. Check out this link for more info. I know my gas mileage dropped by 4 points in early november, as it always does. If you live in a rural area, I think they don't have this gas so you wouldn't notice the drop.

Steven

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I've heard this same thing before!

Originally posted by ssolomo:

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They call it reformulated gas or oxygenated fuel. Most metropolitan areas with pollution problems are required to use it in the winter months. If I remember correctly, it is formulated to let off less CO because the atmosphere can't absorb it as well. For some reason, it doesn't burn as easily so your gas mileage drops. Check out this link for more info. I know my gas mileage dropped by 4 points in early november, as it always does. If you live in a rural area, I think they don't have this gas so you wouldn't notice the drop.

Steven
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'98.5 Silver Frost SVT with winter gas mileage

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You know this is great, lets make a gas that lets off less CO (good thing), but than makes you burn more of it! Someone at the gov had to think of this.

Originally posted by kinger:

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You know this is great, lets make a gas that lets off less CO (good thing), but than makes you burn more of it! Someone at the gov had to think of this.

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LOL! You're probably right. Either that, or somebody in the gov't got a nicely enlarged wallet to implement this.

I also thought that since the engine does not run as hot in the winter that it wasn't as efficient either. Also on a cold start up on my V6 it'll burn through an ubsurd amount of gas unless I start driving almost instantly. I don't have this problem in the summer though.