Just clipped the 1300 mile mark, been running 91 or better octane (ethanol free) about 50/50 highway and city miles.
So far I am pleased with the MPG's, still in the 20 MPG range. Amazing how the 3.5 EB lays the power, seem to pull no mater what RPM range I am in.
Looking forward to throwing some custom tunes into this engine very soon.

 

I'm not sure about your interpretation of huge. To me, 20% is a huge drop in fuel economy. Just saying. Back when the gas prices were down below $2.00 per gallon, I might have agreed with you. Now, with Regular approaching $3.00 per gallon again, every little bit is important. My 2011 5.0 still gets 20MPG+, and my wife's new Expedition with the venerable 3.5 EB gets about 18 when she drives it and 21 when I'm at the wheel. I just hope it doesn't get back up to that $3.50 range we had back in 2012, which sucked, but not as bad as the $4.00 back in 2008-2009.

 

Just got back from a trip to Santa Fe, overall mileage 20.4. 2018 F150 5.0 3:31 e-locker Fx4.

 

Just returned from Santa Fe New Mexico, computer and hand figured mileage; 20.4. Combination of highway, city, and mountain driving. Highest I saw on the lie-o-meter was 29.2 at 55mph speed limit.
2018 FX4 5.0 10 speed, 3:31gears.

 

Just filled her up again, got 19.2 mpg in 90% city driving with the AC on. Computer says 20.5 mpg. Did have more idle time this tank than usual. Have 2300 miles on the truck.

 

I get about 18 mpg about 65 mph. Over 70 mph I get about 16. I usually cruise abour 68 to get the best overall mileage.

 

PursuitAngler, which rearend is in your truck????

 

I have been watching this thread with interest and dismay for a while.

I finally realized that almost ALL the higher mileage reports were from folks I am sure did not do very much towing and drive slowly. I can get fairly high numbers, just not as high as I have seen reported very frequently. I do get better numbers when forced to cruise slowly without my appendage (enclosed cargo trailer - 7x7x14) attached, but that does not happen very often. I also noted that a lot were from smaller engines than mine and quite a few of those were NOT 4x4's. This actually speaks directly to and of the lack of fuel economy numbers for the SD class truck. Different utilizations will always give different economy results.

I tend to get between 17.4 and 19.6, unloaded. When the appendage is attached the numbers vary between 7.6 (at ~80mph) to 11 (at ~60 mph) but don't seem to vary much according to how heavily the trailer is loaded. My lifetime average is just over 12mpg, but I have towed for a full 1/3 of the trucks 18,000 miles.

In short this thread is beginning to look to me like a 'feel good' thread rather than something I might be able to use as a basis for planning.

 

We are in Ohio to help my daughter move, current dash reading 22.3, overall avg. is 20.5. Been running the speed limit +5 all day. 2018 Fx4, 5.0 3:31 gears, 4x4 Scab.

 

Towing or just the truck? It makes a huge difference.