Hi,
Just checked the vms on my 330hp cat C7, 40 foot 34000 lbs including tow car, 7.9 mpg overall burning 4262 gallons. I would say 90 percent of time I am towing. Cruise control set at 62mph, trans in 6th in economy mode is how I run on flat hwy. Mountains I cut back to 54mph and economy mode off. When I drive this coach with the cruise off I get less mpg.
See you out there.
Charles