Frank Swygert
Well-Known Member
I get an average of about 13.5 with mixed city/highway driving with my 2005 (4x4, 5.4L, four speed auto, 3.73 gears -- tow package). That will put it at 10-11 city, 14-15 highway. I only get that mileage because I hardly ever drive it over 65-68 mph though. Tests back in the late 70s showed that aerodynamic drag increases exponentially over about 65 mph. Most vehicles were pretty much bricks compared to today's, so you can probably up that a few mph, but big trucks with large frontal areas aren't going to do much better. Just rounding corners does help though. If you're running 70-75 or taking off hard and fast a lot gas mileage is going to drop significantly. Mine drops to 9-10 mpg when towing my 7000# camper. I'm right at the max recommended payload when packed up for towing. If I boondocked with it I'd be 200-300 pounds over the tow rating . As it is I don't carry water in the tank or a generator, just use campgrounds with power and water.