I have had 350 and 450 chassis small Class Cs over the years with the V10. Nine. Good days more. Bad days less. I am on target with Joseph in his post.
If you look at the TOTAL cost of owning any motorhome and consider depreciation, storage expense, insurance, license fees, annual inspections, maintenance etc., I think you will find the difference between nine mpg and 14 mpg in actual cost of fuel compared to the other expenses to be less meaningful than you might think at first blush. !0,000 miles a year at 9 is 1111 gallons. 10,000 miles a year at 14 is 714 gallons. Now, that is almost 400 gallons difference which may be about a thousand bucks a year. The average owner doesn't drive 10,000 miles, maybe half of that. We drive about 6000 miles a year and spend about six weeks a year in our PC.
Money is money, but compared to total cost, I just never worry about fuel cost that much. One thing I do know, that V10 can pull a lot of weight and is a very reliable chassis.
I don't mean to be flippant about spending money on gasoline, but compared to storage costs and depreciation, it just isn't that big a factor for me.
Paul