Anywhere from 9.5 to 11.5. Seems the wind plays a big role. I have been running 5startunes (93 & 87 performance) and stock still gets better fuel mileage consistantly. This is trended over a minimum of 5 tanks each tune. 93 performance is the worst but not that noticeable with ave. mpg at 10.1 and stock getting ave of 10.8.
1999 F350 4x4 5.4 gas, 5 star tunes, SPD Y-Pipe, 4.56 gears, procomp trac bars, 35" A/T cooper's, 16x10 Ion -38offset wheels.
"My truck can get me out of trouble but I don't go looking for it."
I have been tracking my mileage very accurately, being an Engineering student. It has been right around 0 degrees and all of my driving is in 4x4 and on hills. I try and keep RPMs low. The last two fillups have been between 8.1-8.4.
2008 F350 5.4L crew cab, long box 4x4. I've been hand calculating my miles (although the dash calculator has been fairly close) stock (original tires from when i purchased it a couple months ago, aired to i have no idea) i went through several tanks at about 60% freeway 13 overall average mpg. i then installed a 5 star tune (87 econ; also brand new E rated tires to 65 PSI - thinking about messing with tire pressure, but don't know if it is worth the hassle) and i've run 3 tanks through it now, i've had an average of 14.4. when it was a little warmer, i was actually at 15.1 but the last tank really brought me down. I think that my 4x4 hubs aren't fully unlocking (just going by road feel). i've got shocks on the way, going to rebuild the hubs at the same time and see if my suspicion was correct.
Jared in Eaton Rapids, 2008 F350 5.4L CCLB
"Life can only be understood backward. It must be lived forward." F. Scott Fitzgerald
2000 F250SDLB 4x, new Jasper 5.4 2v, AMSoil in every box, AFE intake, Magnaflow muffler.
10-11mpg city on winter blend fuel
14 hwy winter blend fuel
add 1-2 mpg in summer. DEQ up here adds to much crap to fuel.
I have just installed a new x pipe in front of cat that made a huge difference in performance now I am checking mileage.
I will look at Transmission slip and a programmer next.
2235 miles in 4 days. 85% highway, 10% city, 5% in 4x4 through a few inches of snow. On the highway, averaged 75-80mph. A couple hundred pounds of me and a couple hundred pounds of gear was the only cargo.
The only add-on that may (arguably) have helped with mileage is a tonneau cover (that failed in the last 200 miles).
Computer varied between 12.3mpg and 13.6mpg during the trip, but said 13.1mpg when I got home. Hand calculated, I got 13.4mpg for the whole trip.
A little better than I was expecting, but still no where near what I got on a very similar trip with my Duramax a few years ago. I think I averaged 21 or 22 mpg empty. But, the upfront savings of buying the gasser will still save me money in the long run, though.
I just bought a new Prius to use for my work route vehicle and the Mrs is driving my F250. My 14~mpg very light city in the F250 went to 11 with her driving her short 6 mile each way commute. The Prius is returning 50-53 mpg per tank averages city and 47~ interstate at 74~mph. This way I get to keep the truck and make some money with mileage reimbursements.
2010 F250 XLT CC SB 4X2 5.4L auto/3.73 Reese 15k
2007 KZ Jag 28JFSS 5th wheel. 8500# 1700# pin.
As a daily in town drive I avg 13.7 mpg and on the Highway about 18.5mpg but I have the family with me when on the highway. Just got finish with a trip to Corpus Christi and I managed about 9.5 mpg coming back and on the way there I only got 8.5. Not to sure of the difference other than the tail wind coming back. My travel trailer is 33.3Ft long and weights about 8500 loaded. I keep it dry till I arrive on site so its about 7800 when towing I think. about 1000lbs of passengers....yaa were a bit heavy too. I was very impressed with the 5.4L easily pulling the load and not once did it over heat and I maintained 65mph the entire trip. I always set the cruise so I can concentrate on the road more. It will get up to 75 and 80 effortlessly but that's just not safe with a trailer. Hope this helps someone who might be wondering about the 5.4L. I have been thinking of a 2014 Platinum Long wheel base 4x4 with the 3.5l Twin turbo since I don't pull often and it would definitely be a better daily drive and supposedly pull with more power but im still satisfied with the 5.4 knowing it has to strength and was actually used for the F250's just a couple years ago.
Last edited by Gary Staines II; 06-29-2014 at 10:43 PM.
Reason: added the in city driving
Glad to hear Im not the only one that's horrified by the terrible mileage. I have a 1999 F250 SCab 4x4 super duty w/I think 3.73 gears all stock except for the K&N filter w/only 60,000 mi on it and we get a consistent 12mpg. Its going to be for sale very soon as much as I like the look of the truck, its also gutless compared to our 93 Dodge Cummings E250 4x4
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