GTY, for some reason...and it doesn't involve driving like a grandma...I think I've always been able to achieve EPA mileage ratings, and often even exceed them...at least the highway estimate. The in-town stuff is often all over the place. Their highway stuff doesn't seem too hard to achieve, though. I imagine your signage and such doesn't help your mileage much, does it.
I have a buddy in our local dirt motor club who does the same thing you do with his own business here in the area.