we just purchased a winnebago, on initial trip mileage appears to be in upper 9's without a tow vehicle. Went from Prescott Az to Lakeside to PHX, home to tucson. Have not filled up since getting home to close out but it took 24 gals for 1st leg of 240 something, and estimate of 26 -27 for final from showlow, total mileage almost 500. Some pretty good pulls all directions plus strong winds.
I am contemplating a tuner from 5Star which they say will improve shifting and transmission operation, throttle control and improve the mileage a little.
There are several posts on mileage and most seem to be in the 8-10 none tow and around 8 towing! Yours may vary