Best for me was 28.5. It was winter, almost flat driving, and I had the cruise set at 60 mph, on a strick Hwy trip.. Surprised me. I made sure I topped the tank before and after on flat ground. I regularly get 24-24.5 on the Hwy when I go 65-70 mph. Around town(Houston and surrounding areas) I average 17.5-18.5.

 

Average for me on the highway is about 19mpg.
That is with just the tools in the tool box, about 700#
Around town is a whole different story, it varies from 10-15mpg.
Usually loaded with 100 gal transfer tank, trailer, skidsteer, whatever attatchments I may need for the day.
But remember this, if it were a gasser. Cut the mileage in half,
And you wouln't have that silly smile on your face when you pull off a red light with a 10k load and keep up with traffic! ;D
Rich