My impression and I may be wrong is the generator use won't show in the miles per gallon numbers but after a while as the the tank level drops it will update miles to empty. So if at one point it shows 400 miles left to empty and the generator continues to be used you it may only get say 300 more miles (understand these numbers I am throwing up are not real) but as the fuel tank level is dropping faster the miles to empty would keep readjusting, I've always thought it calculated average mpg compared to current fuel level in the tank. Again I may be wrong and since I don't have a MH, I can't speak to actual generator use while going down the road.
Dale & Terri, Lulu & Tiki (our Chihuahua's), New rescue puppy Prince - Pom/Pug mix.
2013 Tundra, Double Cab, 5.7, TRD Off-Road, 4X4, Full Tow Package
2013 Wildwood T26TBSS - Sold
2000 Gulf Stream Sun Voyager M-8357 MH, Ford Trident V10 Gasser, 35 foot.