First "long" trip with TT.

Wind drag is what drags your miliage down. My 06 dually with a cummins and G56 and 4.10's Gets 14 or 15 carrying 4,000 pound truck camper. And 11 or 12 towing 21,000 + pound Jayco Recon 36V toy hauler.

I have since 1989, been saying; If you can get that kind of mileage, bring your pickup and I'll let you hook on my Arctic Fox. I will bet you all the fuel you want to burn you can't get over 10MPG from N Va to Ohio and back via RT 7, 522, I 68 and I 70 then down I 77, I68 to I 81 and back here. No one has ever taken me up. I have driven 3 diesel pickups into the ground and you need to go get the HP developed/lb of fuel burned formula and find out what you do burn in your 300 hp Cummins.

http://performancedevelopments.com/fuel-flow-calculations-for-horsepower/

I get about 11.5 on level ground with my 2011 F-150.

Pulling a 28 foot TT with a 2015 GMC Sierra I can go through a half tank of gas in 2 to 3 hours of driving depending on the amount of hills etc. I have a rule that once I hit a half tank of gas I start looking for fuel.

I have an E-boost F-150. I get 10 mpg average. The worst was 7.5 mph against strong head winds, the best was 12.7 with strong tail winds.

I do not pay much attention to short trips under 1000 mile because the day to day variance is too great.

On a 1000 mile trip I burn 100 gallons. So 10 mpg is what I budget.

afidel wrote:

MFL wrote:
OP stated "We went from Evanston Wy to Mesquite Nv". That is going from a mile and a half high to a quarter mile high. You could have just put transfer case in neutral, let her roll, and had trip average 20+ mpg.

Anyway, Ford truck, Cummins engine, great job, must have been a fun project!

Jerry

You missed the 'and back' part, they had to gain all that altitude back.

While my post was TnC, didn't miss anything. If coasting, using NO FUEL to get there, and worst case coming home 12.7, still nets 20+ average.

Jerry

afidel wrote:

MFL wrote:
OP stated "We went from Evanston Wy to Mesquite Nv". That is going from a mile and a half high to a quarter mile high. You could have just put transfer case in neutral, let her roll, and had trip average 20+ mpg.

Anyway, Ford truck, Cummins engine, great job, must have been a fun project!

Jerry

You missed the 'and back' part, they had to gain all that altitude back.

Couldn't quite let it roll, but it was defiantly easier going than returning home. There are a couple passes where you climb back to 6500' around Cedar City Utah so it got a work out both ways. I think if I had skipped the last 100 miles in my calculations I'd have been pushing 17 MPG average.

ScottG wrote:
What year is the Cummins?

'89 Cummins, NV4500 transmission. 3.54 gears.

Hard to believe someone can get 17 mpg towing a TT like that. We usually get 8-9 mpg with a V10 F250 with 4.1 gears and 29' TT. It is what it is and I don't worry about it anymore.

The cost of gas has skyrocketed here lately and is now over $7 US a gallon. Not good for RV-ers... :( They are blaming it on a production shortage but why does it always go up every year in time for the better weather, pffft. We do all our RV-ing in the US so they're not accessing any of our cash. :) Now, if the exchange rate could only return to around par.

MFL wrote:
OP stated "We went from Evanston Wy to Mesquite Nv". That is going from a mile and a half high to a quarter mile high. You could have just put transfer case in neutral, let her roll, and had trip average 20+ mpg.

Anyway, Ford truck, Cummins engine, great job, must have been a fun project!

Jerry

You missed the 'and back' part, they had to gain all that altitude back.