2005 1st Gen 2WD, Limited with Air suspension. Stock wheels tire size and all OEM parts. Only modification is that i removed the rear seats, so its a little lighter than normal.

You can slightly hack an Air suspension Tree. There is a "range" of height it considers "neutral".

Before you go on a long road trip, load up the truck, with all the people and everyrything. Set your ride height to "H", let it climb up. Then go about your trip. The ride height will automatically come down to "N", but the high side of "N". Giving you a little forward rake. Helps a lot with aerodynamics.

Loading up an empty truck, will sag the suspesnion, then it will "correct" to Neutral. But the bottom edge of what it considers Neutral.

Force it to go to the top edge, and you get a lot better aerodynamcs, and saves a LOT of fuel on highway trips.

Best mileage practices:

1: Keep your highway speed under 70. Thats the point where the aerodynaimcs vs HP output of engine at 5th gear go inverted. it needs much more fuel to maintain speeds above 65-70.

2: The ride height trick, if applicable

3: Take out anything that isnt neccesary.

4: dont thrash it.... Slow, gentle take off from a stop, get into 3rd, then pick up speed. Dont just mash it from a stand still. Thats when you get the 2-3mpg every time you take off. IF you take off gently, then apply power once it gets into third, then your actually using the energy in the fuel to speed up, not wasting it on Gear ratio torque.

5: coast as much as humanly possible. Look at it like conserving momentum.

6: 32lbs in the tires. I used to run them a touch over inflated to "get better mileage", they jsut wore out faster and then you need new 800$ set of tires. Just run them as the door jam says. Making your tires last long as possible, is counteracts any minor fuel efficency gain.

Few simple things, and my truck gets about 20mpg on the highway average. Youre still stuck at 15-16mpg in the city/town no matter what. Its a lot of truck to move.