just another mpg figure for people to reference:
my scanguage II lists my average mpg at 16.5.
the speed has been gps calibrated and my "miles till empty" is accurately calibrated to within a mile (+or-). so i assume 16.5 mpg is accurate.
daily commute includes 80 miles of highway driving and 10-15 miles of city.
edit: stock tires and a/c on low 25% of my drive time (guestimation)
edit: edit: i began using cruise control for my 80 mile rt commute and have increased my milage to 17.6. It doesnt sound like a lot, but it's another 20 miles a tank....