My truck used to get great gas mileage on the interstate doing 73-75 mph. I made a full 5 1/2 hour trip to the beach in it and got down there with a third of a tank left, but now, when i drive it 30 minutes to school and 30 back it uses a full quarter a tank. I haven't changed a thing on my truck in that time but its just decided to turn on me haha. Used to when i filled it up it would stay on full for an hours worth on the interstate, now, maybe...10 minutes

Just checked my 4.2, 4X4, stick, stock, tires, etc. 18 every day driving, 13.5 pulling Mustang on trailer at 70 MPH on freeway.

If u go bigger say u have stock tires 265-60-16 and go up 2 sizes 285-60-16 and your speedo reading 60 mph u really @ 58.3mph if u don't recalibrate speedo u will think u r getting better mpg is most peoples problem and @ 140mph on speedo u really @ 135.5mph not that anyone drives that fast in U.S.A.