I'm a Cali driver. 55 all the way. You can average 58 all the way to new York from wa. Your mpg suffers in the west but once you get out of Montana, your mpg gets higher. All depends on your shifting.
Geez, and I remember when guys were bragging about 7's. Heck I would have been ecstatic with 7's in my old Pete 379.
it's not hard to get 9+. all you gotta do, is BOBTAIL. and drive the middle flats of the country. i have a hard time beleiveing anyone can get 8. let alone 7. pulling 80k. i pull a flat, in the mountains. and 5 is hard. heavyweights can't even get 4.5. and THAT'S the REALISTICS. even with an auto.
Got 8.1mpg last quarter. Average gross weight, including deadhead, was like 65,000. But most of my miles were in the midwest flatlands and I generally drive 55. I hate hate hate crossing the continental divide when it comes to fuel economy. Can do everything perfectly and still only average 6.5...
I can get over 7 at times, last two ifta quarters were 6.7 /6.68. 97 pete 379 15 speed 3:55 rears. I installed the c18 boat cam and upgraded the turbo and run a cat 5ds 601 2049 file. Always near 80k out back hauls 20% of the time. I try to keep my speed at 64 or less. Oh by the way I never drop more than 3/4mph from my cruise set, unless I run to Kentucky I will loose 8/10 on the Covington hill on 75 South. So yes I say with the correct setup 9/10 mpg should be very easy. Before fuel went down I could turn a profit on the surcharge at my numbers.
It's done every day drivers.....MVT out of Los Cruses gets a fleet avg of 9.3 with Prostars fully loaded.........with vans. No kidding......
I drive a 13 ProStar with a 400hp ISX15ST and a 10sp auto shift...9+ with a MT 53, 7.0-7.5 with a 44,000lb in the trl @65mph. 7.5-8.2 with 20-25,000lbs....it is possible depending on how the truck is setup.