My 06 Dodge with the 5.9 gets an honest 19-20mpg kicking around town and 23-25mpg on the HWY. That is if I keep it under 75mph laugh I check it the old fashioned way and don't trust the "Overhead Liar"
I have a few power adders that increase the HP & torque and have actually INCREASED my fuel economy (cold air kit, Smarty, etc).
Again, all is good if I keep my foot out of it. But, I do like to see it smoke and hear the turbo sing laugh

If your going to tow, then diesel is the ticket.
_________________________
Netting = EXTINCTION