I've made a lot

of improvements to my 10th Gen I've shown before. Hope this benefits some of you:

Will Shorter Gears Impact Fuel Economy? 3.55 to 4.10 Gear Change ’97-’04 10th Gen F150 Test @ 65 MPH:

You Tube

 

So, mileage differences obviously vary depending on speed, driving types, conditions, going easy on the gas pedal, load, geography, city/hwy, etc. The best mileage that I ever got was when I drove a new rental F-150 Platinum with an ecoboost throughout the Carolina's and got in the low 20's with relatively flat roads & lots of highway driving.

But here in the Northwest, I consistently average 15.5 - 16 mpg with my 2015 3.5L Ecoboost over 75,000 miles. I got the same mileage from my previous 2015 F-150 3.5L EB, and slightly worse mileage from my 2013 F150 5.0L. Important to mention that I'm Not driving in eco mode, or at/under the speed limit, or trying to get the best fuel economy that I can get. I drive my trucks hard accelerating away from stops fast & I'm always driving 5-10 mph over the speed limit and doing at least 78 on the freeway. I'm pretty pleased with my real world mpg fuel numbers having 10-ply tires on my truck, and a heavy folding bed cover, and considering that I drive hard without regard to fuel prices or economy in an area of the pacific northwest with stop lights, hills & windy conditions. I really think 20+ mpg would be difficult to reach or average in the area that I live in given other F-150 owners that I've spoke with over the years here.

Btw, I just averaged around 9.5 mpg over a 2100 mile trip to Wyoming & Montana pulling my 9,500lb trailer (or 8 - 8.5 mpg if just looking at tow numbers only). And I towed hard as usual Up passes, and at 72-75mph on the freeways. My Ecoboost towed awesome over huge climbs, and through 105 degree conditions. My buddy did the same trip with his newer 1 ton Dodge, and he averaged 10.5 - 11 mpg for reference with a slightly heavier trailer.

Hope this info is helpful.

 

My '17 Lariat screw/FX4 gets to tow a 7x7x14 trailer about 30% of the time. With the trailer on I used to get 5.8 to 6.4 mpg on the highway (running at speed limit +5, but in Texas that means between 75 and 85). I tend to drive like you do but have found a reasonable solution that works for me.
I switched to premium fuel and over time saw the difference in mileage when not towing go up. Sometimes it made the increase in fuel cost worthwhile, but generally no. Regular around town was getting between 17.8 and 19.1 but on premium it gets between 20.1 and 21.5 - NOT WHILE TOWING.

HOWEVER when towing the trailer I saw a constant 30 to 35% improvement in mileage. Last trip got 9.7 mpg.

There are 2 issues here. The first issue is that the computer always looks for the leanest it can run the engine, which is defined by just before knocking occurs. With premium that happens later which means the engine is leaned out more.
The continuation of that issue is that mostly the improvement has been seen on the highway because that is where then engine is nearing its peak performance.

The second issue is the 'gottcha' of this. It is NOT instant! It takes 2 or 3 tanks to get the computer trained correctly.

YMMV - but I am sold based on experience.

 

Here is what my 2018 has been getting. I traded it in last night for an F-450 Superduty. Sad day because it was a wonderful truck, to drive, and troublefree for over 62,000 miles. The Magma Red with Marsala is a great combination too and just wish I could have found what I got in the same color, then I wouldn't feel so bad for trading it in.

The one thing I will regret is when it comes time to fill that tank! Still cheaper in the long run than having and maintaining 2 trucks, and the Superduty I had sat more than it was driven, which is also not good for it.




Going to miss My Precious.

 

My 2017 2.7 EB 4x4:

25.7 mpg on a 345 mile mostly highway and state highway roads. Cruise set at 72 mph on the highways. 55 -60 on state highways. 91 octane ethanol feee gas.

Same trip back towing the airstream back got 15.4 mpg.

 

If you can verify with the hand calc, that is impressive. Trust, but Verify I always say.

 

I didn’t verify this one, but have hand calculated many in the past. I had already gone into test mode and sync’d up the lie o meter to be accurate.

I was surprised. I always got about 21-22 max mpg using 87 but get pretty decent numbers switching to 91 non ethanol and 93 premium.

 

Before I traded the F-150 in, the 3.5 was getting over 23 MPG, LOM showed it ~ 22.

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I’ve calculated about 40 tank fills and found at the most it was ever .5 off so I stopped calculating every time. I could have been getting over 26 there or 25 even I suppose.

 

My 2016 2.7 2wd 157"wb Lariat has gradually crept up to 21.2mpg (trip 2) over it's 94,000 miles. It's had a steady diet of Shell 87. I accurized the "lie-o-meter" (dropped about 1.5mpg's, which hurt my feelings...) a few years ago, so the 21.2 is pretty close +-.
Speed, hauling, towing, wind, temp and winter blend gas all have an effect.