Their have been alot of good reasons given on how to improve ones gas mileage, (tire pressure, winter idleing,ect.) I work as an engineering technican and when checking your mpg make sure it is all hwy or city miles. I like filling up next to the Highway I'm driving and filling when I get to the destination. The 06 SE Fusion I had could get 31mpg hwy and 20 city. Other factors would be a head wind, climbing in elevation, AC on or off and also type of fuel Ethanol(10% alcohol) will get worse gas mileage. MY 08 Tauras gets18 city and 29 hwy. Ive heard that the 2010 I4 numbers can be as high as 34mpg maybe that will be my next car.