I'm not complaining, but I too wonder how some of these trucks are supposedly getting 18-20 mpg driving 80 mph while I'm using the cruise control and staying under 2000 rpm. The power this thing makes offsets the mediocre mileage but I don't understand why we're not all averaging about the same mileage.
My late father-in-law used to say, “There’ve been more lies told about sex and fuel mileage than anything else”. 😆 I’m certainly not accusing anyone here of being less than forthcoming with the truth. I just thought it was funny.
Anyway, I wouldn’t really expect our trucks to be anywhere close in fuel mileage. Driving style & habits account for most of the variation as well as things like tire pressure, load, terrain, modifications & other factors. Cruise control is not the friend of fuel mileage. The only thing it will do is hold a constant set speed. Your mileage would be better if you held constant pressure on the throttle, allowed the truck to slow down going uphill & regain the speed going back downhill (traffic permitting).
Just as a point of reference, my 4 door 4X4 dually with 3.73 gears gets 15 - 16 mpg solo (using the driver info display). I consider 15 mpg to be adaquate & 17 mpg to be really good. Towing the 16,400 pound 5th wheel in my sig, I can depend on 9 mpg & Im really happier if I just don’t look at the mpg when towing. ☺️ I’ve often wondered if 4.10 or 4.30 gears would yield better mileage towing this heavy 5er. The truck tows great & I’ve had no problems.
To make a long story unbearable, I don’t think there is anything wrong with your truck. Just drive it & enjoy the ride!
2013 F-350 Lariat 6.7 L PSD Crew Cab Dually, FX4, white platinum metalic tri-coat with black interior, N-Fab step bars, factory spray-in bedliner and 5th wheel hitch, trailer tow package, integrated brake controller, upfitter switches, Sync with My Ford Touch, memory group, remote start, reverse sensing with rear view camera, nav, satillite radio, Weather Tech floor mats, limited slip diff, moon roof, climate controlled seats, engine block heater and tailgate step.
2014 Lifestyle (formerly Carriage) 5th wheel 38' long with 3 slides & all the goodies.
SOLD: 2005 F-350 Lariat, 6.0 PSD, Torqueshift auto trans, crew cab, SRW, short box, FX4, ESOF, limited slip dif., tow command, upfitter switches, 6 CD changer, Lariat Lux. package, camper package, engine block heater, triple A-pillar gauge set (Autometer) with pyrometer, trans temp & voltmeter, MBRP 4" cat back exhaust w/5" dual wall chrome tip, dark shadow gray/ med. flint interior.