About 18-19 in town, 19-20 highway, 10.1 in our Tennessee mountains, 11.2 on Georgia's and Florida's flatlands. I'm running my GMC 2007 (new body style) stock with 6-speed Allison. Towing 2008 Landmark Cape Cod with generator, full propane, 12 gallons gasoline in gen tank, ~30 gallons of water...