Jan-Ola, I figured my mileage after I have my gasifier warmed up, just a little Dino being used at start up. I top off my hopper before I leave the house to check my miles per pounds of wood. At my normal driving habits, I am getting 2.5 pounds or more wood, to every mile. Trying to get it down to 2 pounds but there are a lot of hills to climb in my area. 318 cubic inch engine and a heavier truck. I think you are getting very good milage out of your gasifier truck.
Like Kevin said, warming the gasifier up takes a few pounds of wood in colder weather so I never count it against my mileage. Heck it just wood, not Dino fuel. SWEM