Gas Mileage Ford Fusion

I have a high mileage 121,000 Ford Fusion. I had the transmission flushed and gas mileage went down from 29 to 26. Then i had same shop do a tune up and air filter change. The mileage continues to drop. Does this make any sense?

Fuel mileage drop is likely do to colder temperatures and winter blend fuel. I have lost 4+ mpg since the weather has gotten cold.

Thank You. It's just weird right after they flushed the transmission when it wasnt cold the mileage starting dropping. The tune up was more recently when it got colder. I drove over 500 miles of nothing but highway and milage started out at 26.4 by the time i returned it was 25.8. It was all highway. In the past when car was newer after these highway trips sometimes the mileage would go up to 32 and then slowly drop after returning to normal driving down to about 29.5. After the transmission flush about 6 months ago the mileage dropped to 26 and has never gone back up. Is it the high mileage 121,000? Car shifts fine I'm pretty sure flush was fine. The shop says flush would not affect mileage. They suggested tune up and new air filter. After tune up which was done in this cold weather i have still seen no change. Should i try additives to gas ?

What Stealthee was getting at is that the oil companies change the additives that they add to gasoline during winter months. This is done primarily to make cars easier to start in cold weather. The 'unwanted' side-effect is a loss in fuel mileage due to the winter blend's lower octane. Your car's electronic systems sense this change and tell the engine to use more fuel.

The only other thing that I can think of that that >>might<< cause the lower fuel mileage would be if one or more injectors was sticking. Using a fuel injection cleaner like Lubro Moly's "Jectron" (my pick) or Sea Foam's "Motor Treatment" in the gas tank should remove any 'varnish' build up in the injector tips. Neither of these treatments will harm your engine if used as directed.

Most of us who have driven for years, however, have just come to expect lower fuel mileage in the winter and don't worry too much about it.

If you live in a climate with snow you'll get less mileage driving in snow and ice than you do on clean asphalt.

Driving on snow and ice against clean asphalt will make a negligible difference. Besides most places will have cleared roads so the difference is still in the temperature, fuel, and warm ups.