First long pull

This may be a little `heavy' but the force needed to pull the house down the road varies with the speed. For example if you increase the speed from 40 mph to 60 that increases the speed 1.5 times but the force 2.25 times.
We get around 6 mph at 60 mph against the wind towing 7500 lbs. Your 9.5 is a little better than we get on average; 2011 3/4 ton Suburban with 6.0 L engine.

your doing better than our son's work F250 gasser. He pulls a 28 ft Vnose that weighs about 7500 lbs. Best he ever gets is 9, more often barely 8, sometimes as low as 6.

And it isn't that he is going fast, working for the state one thing one NEVER does is go over the speed limit and they actually pretty much require him to follow the truck limit, even though legally he doesn't have to. So..... he's seldom over 60, and most of the time he is on rodes with a 55 limit.

His previous truck was a Dodge with the 5.7 hemi. Mileage wasn't noticeably different with the Dodge.

"Do I have an unrealistic expectation of 12 or better?"

No, 12 or better is not unrealistic. But more likely with a lighter TT, slow 55 MPH, flat ground and new truck - more fuel efficient. Did you have a head wind?

dadechil wrote:
Pulled yesterday ( 400miles) with my new to me 99 f250 sd. Pleased with the power but a bit disappointed with the fuel mileage (9.5 mpg ) when we stopped at 300 miles. Do I have an unrealistic expectation of 12 or better. I used to get 8mpg when I towed with a 07 Chrysler aspen hemi.

99f250sd long bed 7.3 king cab. 2017 heartland pioneer bh300 dry weight 7000. Loaded 7700

While I suspect 9.5 is a bit low for that engine, you do realize you went from a vehicle that had a curb weight of nearly 5K lbs to one that has a budget busting curb weight somewhere north of 8000 lbs!

Nearly 3K lbs more than your previous vehicle!

With that said, I suspect your 7.3 should have been a bit better than 11 towing that weight.

I would be a bit disappointed myself with that especially since I have a 2013 F250 Super cab with 6.2 gasser hauling about 7K lbs and my most recent trip I had a low of 9.6 and high of 10.2 towing at 68 MPH..

But, for budgeting purposes just figure roughly 10 MPG and you will most likely have enough budget for your trip.

I get the same mileage with my F150 and Nash 22h.
As others have said, you're pulling a barn down the road. Gas mileage is going to reflect that.

It seems low but I usually drive 60 pulling 12,xxx FW and 2800 lb utility trailer and get 10. I pulled another FW 1400 miles at 6o mph about 9800 lb and did 13.4. 2014 CTD 3500 3:73 running in 5 th gear

dadechil wrote:

dadechil wrote:

Winnebago Bob wrote:
Mileage sounds reasonable without knowing the speed you were traveling.

Can't find your model listed anywhere..

65 mph. 2000 rpm

https://www.heartlandrvs.com/brands/travel/pioneer/pi-qb-300

Has the upgrade towing package so does have a huge trans cooler. Like to know my fuel mileage as it helps to figure that $ into the budget

dadechil wrote:

Winnebago Bob wrote:
Mileage sounds reasonable without knowing the speed you were traveling.

Can't find your model listed anywhere..

65 mph. 2000 rpm

https://www.heartlandrvs.com/brands/travel/pioneer/pi-qb-300

You should be able to get over 12 mpg BUT you'll have to slow down to 45:B Not sure why we worry about mpg on something that gets the least miles/year. Basing you mph on one fill up leaves lots of room for error.

Hope you've added a tranny oil cooler if it's a automatic.

I have to say I would be a little disappointed in 9.5 with 8000lbs. I frequently go as a passenger with my brother and a buddy who has 99 7.3 with a six speed pulling 5000 pound Ideal barn door down the road with 3 dirt bikes in the truck and all supplies and he gets around 12 mpg regularly. So while my comparison example is not quite as high as yours it still seems like yours is a little low. I average 12mpg with my GMC pulling 6000-ish. at 65 mph.