maybe a little irrelevant to van living. but with a 26ft class A, dodge 440, fully loaded. includes 80 gallons of gas and 55 gallons of water, i managed to squeeze a 7.1 mpg.at 55 to 60 mph. mind you that was Glendale AZ to quartzite az.mostly flat ground, and 5.5 from glendale to globe...