What are you getting now and what do you expect?

I get about 16.5 driving in a rural area with 45 mph roads and frequent stops. Get about 17 on the highway if I do about 65, less if I go faster.

To improve fuel economy, slow down. On the highway keep the RPMs about 1700 (65).

Drafting is another good highway choice. Get as close as you can to a vehicle towing a big trailer. This will all the lead vehicle to pull the lag vehicle along. Mileage may vary, depends on how many boys in blue you stop to meet and give autographs.

Gear Vendors makes an overdrive unit to fit on the back of your transmission to give you super overdrive.

I have often wondered how the truck would drive and what fuel economy would be had at 75 mph pulling 1500 or so RPMs. With the torque peak at 1200 rpms, seems as though the motor would pull the truck along quite well empty.