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Interesting mpg last trip

So... My "new" truck is a 2021 F150 with the 2.7 twin turbo and 10 speed trans. In general, this truck tows impressively better than what I had, a 2008 F250 Super Duty with 5.4 and 5 spd torque shift trans.

My 2008 F250 averaged about 10.5 mpg towing on the highway, mpg was falling to 9.5mpg avg when I traded it in.

My 2021 F150, towing the exact same trailers (landscaping and TT), averages 11.5 on the highway.

I average right around 68mph towing. Just habit, keeping it just below 70mph.

I hand calculated mpg for both trucks until I was confident that the truck computer was reading roughly the same. Last camping trip was 2 hours mostly on I95, towing our 21ft TT.

Leaving our house, we hit traffic (not unusual for I95), and went up and down with speed, averaging below 60mph the whole way.

On the way back, we were towing through rain (heavy at times), and definitely averaged 55mph if not lower.

On the way there less than 60mph, we were getting about 14.5 mpg.

On the way home, less then 55mph, we were getting about 14.8 mpg.

I wish I could always tow so slowly to get those numbers, but on a clear day with no traffic I think it is mentally impossible for me to go that slow... lol!

I am completely sold on the new smaller turbo engines. I am amazed at the higher horsepower AND higher torque, AND higher mpg under all conditions I have towed in so far. I am also able to use cruise control much better with the new truck while towing - the truck doesn't kill itself downshifting with high rpms trying to maintain speed - the 10 speed trans downshifts much quicker as needed, able to maintain speed without high rpms.

No, I am not towing a 400ft 5th wheel with quintuple axles, but for me I am very happy with my truck!

So don't poo-poo the new small turbos, depending on what you are towing they may work great for you.
2021 F150 2.7
2004 21' Forest River Surveyor

Below 60 cancels much of the aero penalty. The reason for the 55 in 1974 was that its Rolling Resistance to 45-MPH, and Aero Resistance after 60. 55 is a sweet spot.

The real test is against the TV loaded the same way on the same road at tbe same speed, but without the TT. The percentage change. If you can keep it to 40% that’s spot-on for 60-MPH whether 1973 or 2023.

As tow miles are a fraction of annual miles, the DD numbers are what matter. And where to learn to maximize MPG against the vacation travel. Where the savings are ACTUALLY located.

15.0-MPG is the exact middle of my range when at 60.

Highest highway efficiency will come to a truly aerodynamic trailer, first, and a turbocharged diesel (car or truck), second. There are those with 2006-era Mercedes TD sedans pulling 23’-25’ Airstream hitting low 20’s.

Spec the TV for its DD duties. Pulling a trailer ain’t the job many think it is as they’ve only ever driven around in empty or near-empty vehicles.

The average American runs 15k annually. How much does his average annual fuel burn increase (percentage) as a result of the average RV’ers 5k vacation miles?

It ain’t that much.

Gas DI T/C with 10-Auto? It’s not about the engine so much as it’s the software that keeps temps under control when a load introduced. VVT turbo and Auto-12 in big trucks same way. Computer is in charge.

Cut the aero load, and use CC 100%. No lane-changes or significant braking events. Find THAT sweet spot due to conditions (mainly traffic volume) to cruise above 60 (cancel CC and drop down to get slow passes over; law).

Never join a pack. Or allow one to form around you. Ever. Maintain maximum distance all day (gets easy with practice).

The latest big truck driving as above? These days he’s above 9-MPG with no adverse conditions while grossing 78k.

2004 555 CTD QC LB NV-5600
1990 35’ Silver Streak

8 MPG towing 75-80 up I25 on a rare evening with no Wyoming wind.

2012 RAM 3500 Laramie Longhorn DRW CC 4x4 Max Tow, Cummins HO, 60 gallon RDS aux fuel tank, Reese 18k Elite hitch
2003 Dodge Ram 3500 QC SB 4x4 Cummins HO NV5600 with Smarty JR, Jacobs EB (sold)
2002 Gulf Stream Sea Hawk 29FRB with Honda EV6010

Nomad III
Nomad III
It’s interesting that lower speed would result in increased fuel mileage?
Or a smaller lighter more efficient truck would get better mileage than an older larger less efficient one?
2016 Ram 2500, EFIlive tuned, 5” turbo back, 6" lift on 37s
2017 Heartland Torque T29 - Sold.
Couple of Arctic Fox TCs - Sold

Not poo-pooing your results, but I think it’s very likely that if you went with the 5.0 Coyote, you would also be getting better MPG than the old truck.

I have both a 3.5 Expedition and a 5.7 Hemi in my Grand Cherokee L. When towing my big boat (7000 pounds) the MPG is the same between the two. When towing my fishing boat (3500 pounds) the Hemi is about 20% more fuel efficient.

The EcoBoost is unquestionably more powerful when towing (I might notice this more due to living at elevation).
2012 RAM 3500 Laramie Longhorn DRW CC 4x4 Max Tow, Cummins HO, 60 gallon RDS aux fuel tank, Reese 18k Elite hitch
2003 Dodge Ram 3500 QC SB 4x4 Cummins HO NV5600 with Smarty JR, Jacobs EB (sold)
2002 Gulf Stream Sea Hawk 29FRB with Honda EV6010

Nomad III
Nomad III
Are the cab and bed configurations the same? (ie: 4 door long bed, cap on the bed...etc...). Aerodynamics (or lack thereof) are typically the driving force behind RV MPG...and as you found speed. Also, makes me wonder what was happening with the old F250 if the MPG was falling drastically with the same trailer.

If I was in the market for a 1/2 ton, I would seriously, consider the 3.5EB. I would just keep a close eye on the temps as there is less mass to absorb the heat when doing a long climb, so if the cooling system isn't in top condition, it's more likely to have an issue. I would have no concern with it generating enough HP.
Tammy & Mike
Ford F250 V10
2021 Gray Wolf
Gemini Catamaran 34'
Full Time spliting time between boat and RV

Nomad II
Nomad II
To be fair the old F250 was getting 10 whether towing or not towing.

Putting 10-ply tires on half ton trucks since aught-four.

Explorer III
Explorer III
Good report... If I was in the market for a half ton truck I would have a hard time deciding between the 2.5EB and the 3.5EB engines.
'12 Ford Super Duty FX4 ELD CC 6.7 PSD 400HP 800ft/lbs "270k Miles"
'16 Sprinter 319MKS "Wide Body"

Sounds like a nice truck and an interesting comparison. Certainly an improvement in fuel efficiency. Thank you for sharing.

Interesting that (with your new truck), you are seeing a 22% increase in fuel usage for a 13 mph increase in speed.
I think I'll keep poking along at about 55.