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Gas mileage down for no reason!?

I have a 2001 Saturn SC2. It normally gets 31 to 32 MPG driving about 50/50 city/hwy. All of a sudden my past three gas mileage amounts have been 28, 27 and 26 MPG. I checked my tire air pressure and got a diagnostic at the dealership. They said they didn’t show anything wrong, the air filter was clean, and the engine was not running rich. Last weekend we changed my spark plugs but that hasn’t seemed to help, either. Also, there’s no smell of gas so I don’t think there’s a small leak anywhere. What can I try next? This low mileage is not acceptable!

We’ve over 10 reports such as yours lately. Most could be explained by the very cold weather we’ve experienced lately resulting in poor gas mileage.

To drop your mileage from 31 to 27 is not unusal if the car has to be warmed up, and the cold friction to be overcome in the first few miles. What viscoity oil do you have in the car? Where do you live and park your car. Do you have a block heater in this cold weather?

If you lived in an apartment and parked in a heated basement garage, I would be concerned with such a mileage drop.

Someone else told me it could be related to the cold as well but I live in Raleigh, NC and we don’t have terribly cold weather continuously. Just cold snaps here and there. I normally park in a non-heated garage. I do not have a block heater. I use 5w30 oil as per the owners manual. I use the high-mileage type but I don’t know if that makes any difference. The car has 124,000 miles on it. My commute to work has also shortened from 12 to 7 miles. Maybe it really is the cold? I just can’t imagine I haven’t noticed this in prior winters.

It takes 7 miles to just warm up the car!!! That plus the cold snap could easily account for your mileage drop.