Q: Why has the MPG fallen from 20 to 17 mpg? on 2006 Mercury Milan

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I bought my 2006 Mercury Milan V-6 Premier with less than 25,000 on it. Rode like a dream. Recently, the vehicle miles per gallon has been falling. I have been using the same gasoline (regular unleaded) since I purchased the vehicle in September 2009. The average MPG when I bought it was 27 mpg. Today the average is 20 mpg. As bad if not worse than my 1993 Nissan Maxima, also V-6. What could be causing this problem? The gasoline in my area contains 10% ethanol year round.

(3) Answers
(1) Comments
Possibly its in need of a tune up start with a new air filter and the book shows plug replacement at 90,000 miles
The problem could be the way you are handling the car as well. 20mpg sounds low to me, and 17mpg is abysmal.

In the winter, I get about 26mpg, and in the summer I get 31mpg with my 2006 Milan Premier. I live in MN and our roads aren't that great, so I assume people should get at least as good of mileage as I do.
Have you found out why your mercury mpg was decreasing? I recently purchased a Milan 07 V6 premier and it has been doing the same thing to me. If you can hop it would be very appreciated THANKS
I have an 06 Premier and its gas mog has dropped drastically too. I have had a new air filter and many other tune up items....still not working well. And recently the coolant spit out all over the place and overheated...I think it might be the water pump now..but thermostat has gone out several times. I am not happy with this car's plastic thermostat or all its sensors going bad all the time. This car was a waste of money!