I wouldn’t go by just my first trip unless it was extensive and covered all environs.
Our experience is similar to Stan’s. We hit around 10 on one 600 mile trip (Portland to Twin Falls), but that was with a following wind most of the way, my cruise control on, and above 57mph to keep it in 6th but below 62 for fuel miserliness. Our short coach is relatively light for the engine it has, so that makes hills probably less work.
At times I lean toward obeying posted speeds for trucks, not for the law’s sake but for a general conservation guideline, and not having to pass so many (not that truckers obey it though). On hills it’s nice that as needed the 400 hp can push 36ft easily around bogged down semi’s. Around places like Boise, it’s hard to avoid higher speeds to keep from being an impediment, but at least it’s in 6th.
So as Dave and others suggest, numerous factors and practices affect mileage. Give yourself some time to fine tune and implement habits noted above, Gary, and have CAT certified techs make sure your drive train is optimized.
Joel
