better mpg?

[Field Scout]

Not sure if its from the change in gas formula for summer or that I took my roof basket off so Hummer could replace the plastic roof trim but I've seen a 2.5 mpg increase since dumping the basket. If this keeps up I may have to get something custom done to hold the highlift and pull pal on the back gate out of the wind anyone out there running 33's and no roof basket getting 17 to 17.25 mpg or am I lucky all of the sudden