Our '02 Georgetown 325 (F53/V10) gets a fairly consistent 7.5 mpg. That's a heck of an improvement over our previous rig, an '85 26' Class C with a carburated Ford 460. It got 6.2 mpg at sea level and less than 5 in the mountains. With this rig, fuel mileage doesn't vary with altitude, thanks to EFI.
We run fairly light - 2 people, two Labradors, no toad - and we're usually only out for 10 days, so there's not a lot of "stuff".
Frank and Eileen
No longer RVers or FR owners