WHen I got the truck it was running at a very pocket unfreindly 22L/100km(about 10.5 mpg), now its at a very reasonable 16L/100KM(about 15mpg). Ive done a full tuneup (plugs, wires, cap, rotor, high power coil, serpentine belt), seafoamed it(swear by that stuff now), all synthetic fluids in the truck, took off the topper and the pipe rack, keep the tires at 40PSI, Ive flipped the air filter cover upside down(trailer park cold air intake
) and I got the exhaust done with a flowmaster muffler and some mandrel bent piping. If youre looking for 25-30MPG.....as far as Ive heard. You could try lowering it and a flat underbody, smaller mirrors, carbon fiber body panels(just kidding) but weight reduction will be your biggest helper. Good luck with your project.