[bigearl]

In the Ram or Chevy, if you step down to the 4.7 or 5.3- you might make 20 on the highway. The 5.7 Ram gets about 1 mpg better than the 4.7 on the highway due to cylinder deactivation, but it gets much lower in town or mixed driving so real world- the 4.7 ends up a little better mileage wise. Chevy makes a gas saver version of their truck that runs a 3.03? (I think) gearing with an airdam and a grille baffle that works ok for general hauling from home depot, but you lose a lot of towing ability. Chevy also makes a hybrid that will get you 20. I don't know enough about the current Ford or Toyota MPG to say anything there.

If you can get 16 to 17 in all around driving, you are doing very well by full sized gas truck standards.

As far as diesels go, a used 5.9 Dodge can get you there. It's not unusual for these to average 19-20 in mixed use with over 20 on the highway. The 6.7 will not get you there.