If you poop along at 55 mph and under (try to stay between 50 & 55 mph) you will see vastly improved mileage. As you go drive faster, you will see mileage fall off like a simonized piano. Just remember that as you double your airspeed, the increase in drag is squared. Hence the huge drop off in mileage about 45 mph which on average the most efficient airspeed for most SUV's and trucks. I get between 22 to nearly 25 mph on occasion driving these speeds. It is kinda tough driving when everyone else in driving 75 & 80 mph. I live in the right lane.