Buying fuel is no joke for most of us but I dont consider fueling the Hummers much at all since my boats fuel tank takes 150 GALLONS TO FILL IT UP .
FWIW my supercharged one has the diffs regeared with 38 inch tires and I dont see much difference over stock in economy since the mod. I dont try to give full acceleration unless I really need it so the numbers are about the same.