We see a VERY consistent 9.9mpg (interstate, cruise set at 72mph, generator running), houston to virginia & back. Pulling the Toad seems to have little if any impact (maybe .1 or .2 mpg)
Worst I've ever seen (heavy footed thru mountainous interstate) is 8.6.
BEST We've ever seen is 13.8 (atlanta to destin mixed interstate & secondary roads, w/ generator running, pulling toad)....our average speed for that leg was probably 60-65
in my private storage lot (at least 3 dozen coaches) - it seems most of the pusher owners I've spoken with are lucky to get 8 (if they keep the cruise set at 60/65) - when i say i run 72 they say they would be down in the mid 6's to 7mpg if they ran that fast.
look at it this way - your getting better than most pick-up truck drivers pulling 5er's or TT....and you can use your coach going down the road (they cant)