The new Godzilla produces a lot of low end torque for a gas engine. It's a great engine. But mileage isn't the best. I read reviews that on the F250/350 it's about 14-15 mpg highway not towing. I would guess you'll be in the 7-8 range in a MH. That was just one of the reasons I opted for the 6.7 diesel. I am getting 20-21 not towing and about 14 towing the FW in my signature. Still new to get a lot of comprehensive data but MPG doesn't appear to be the strong suit of the 7.3. It is supposed to be more quiet, and the updated chassis is supposed to ride much nicer.