I have a 2008 Pontiac Wave, Automatic. I get 35MPG imperial. (28 MPG US gallon.) Terrible mileage compared to the rated mileage of 49 on the highway. It is set up to pass the tests, not the real world conditions.
Im having the same issue actually they suggested me to changed the plug sparks i did so a week ago and its been the same so far! i really though the car would give me more MPG