I keep readin these post with people claiming 19mpg with their 5.4L 4x4 raised supercab trucks... I don't know what kind of calculator they are using but it's broken.
I just logged my best milage ever with my 4.6 supercab 2x4 and when correcting for tires, it worked out to less then 16mpg. That was about 340miles on one tank. What gives?? Is my truck really getting that much worse milage??

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Black 1997 F-150 Supercab Flairside. 4.6L with Superchip, Jacobs DIS, K&N Generation II, Cat back Exhaust with Flowmaster 40 and MEG'S Stainless tip in front of rear wheel (nice rumble). 17" Off Road wheel pkg. Lots of body mods. 5 yrs old and still turns heads...and now paid for!! New is NITTO NT404 275/65/17's and Hellwig 1/7/16 front and 1 1/8 rear bar.

 

Well I don't know about the 5.4 but I can honestly say that I've been getting 18 mpg consistantly with my 4.6 if I stay off the gas and drive easy.

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Black
2000 F-150 XLT
Reg cab
Flowmaster
AFE filter (K&N style)
Chassis-tech 2" rear drop

 

I've kept meticulous gas records since I put in my first tank after I drove my 5.4 SCrew off the lot last August 13th. Since then, the average of all that gas and driving conditions has been 16.9mpg.
I added an Airaid on 17 March and my mpg went up consistently another 1.4 miles. Last week I added a Borla split rear and the jury is still out.

 

When I bought my truck, no matter how I drove I got 12.3 hwy & 11.3 city.
Now with 33's and 3" lift I get 11.0 hwy & 10.0 city.
The mods did not make any mileage difference at all.

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1999 4x4 F250 LightDuty XLT SuperCab 5.4L, 3.73, 4R100 trans.
Flowmaster exhaust, K&N FIPK, Superchip, Rancho RSX shocks, Hellwig rear swaybar, Stull billet grille, PIAA Air Dam with 2-PIAA Pro80XT's (85W Superwhites), 4-KC Daylighters (150W), Performance Accessories 3" Body Lift, 33/12.5/17 ProComp Mud Terrains on 17x8 American Racing Atlas Rims. Kenwood 7007 CD, Alpine 3342 Signal Processor, Alpine MRV-F353 5Ch. Amp, Pioneer TS-A6865 3-way speakers, MTX Thunderforms. CompuStar alarm/autostart.

 

just gotta say with my 4.6l, all I get is 13 town 18 highway--and the highway mileage is on a "perfect" day!

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99 F150, 4x4, SC, ORP, 3.55, 4.6l, auto

 

I don't usually post about gas mileage but I beleive it is possible to get 19 mpg, because I can get 18.5 mpg with my truck (see signature) No my calculator is not wrong. I have pulled a 14 ft aluminum boat and an 600lb atv in the back for 250 miles and got 16.2 mpg @75 mph interstate.

However I do usually average between 16 and 17 mpg, but when I baby it, it will go above 18.

Oh and my calculator is a TI-86 and has gotten me to a senior in mechanical engineering, and I have never known it to be wrong.

With alittle better gas, mods, and a couple more psi in the tires I could break 19 easy.

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1997 4x4 5.4 ORP XLT extended cab Dark Toreador red Westin nerf bars tint HARDER THAN A ROCK AND FASTER THAN A HEART BEAT

 

Last time I checked just freeway driving I got 19 out of mine. that is very little city driving, I get around 13 in town.

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1998 150 SC, Lariat, 5.4, Black with a little silver, 4X4, Stock at this time.

 

I would say that yeah, you are just getting lower mileage. Long term average over 4 and half years is right at 17 mpg. Low was around 12 mpg (in -30 degree weather for a long cold snap), all time best for me has been about 23 mpg. See sig for the details.

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1997 F150 XLT, Flareside , Moonlight Blue, 4x2, SC, Auto, 4.6L, 3:08's, Cargo Cover by Century, Penda bed liner, Blue Oval reciever hitch plug, Driver Design bug deflector, Monroe Reflex Shocks, 235/70/16 Firestone Wilderness AT's, sliding rear window, captain's chairs, Valvoline Durablend Oil, Purolator Pure One Oil Filter, 280 lbs. of traction sand (ahh, winter in the great white north! ), and 119,000 miles and counting!

 

I'm ususally gettin about 375 miles out of a tank of gas (17-18 mpg). I love it. I traded in my little Ranger that was gettin about the same for mileage. Now I have a bigger truck and a V-8! Couldn't be happier!!!!!

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1998 F-150 XLT 4x4 SC 4.6L Auto, Class III hitch, Pioneer Premiere deck, Boston speakers

 

Driving back from Atlanta, Georgia to North Carolina, I got 18.987mpg out of my tank before I filled up in Lexington.

5.4 Liter
3.55

 

I will throw in my input on this issue. I will start by saying that there may be ocasions where people can see high MPG with their engine. The problem is when there are some crazy high MPG's, you have to be able to understand when the data is junk. It is possible to get good economy every now and then, but driving conditions will change the numbers drastically.

For what its worth, my truck has 35000 miles and has used a total of 1826 gallons of gas. This gives me an overall average of 19.16 MPG. I keep track of all my fillups and have done mods strictly for MPG.

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My first Baby:
2000 SC XLT Bright Red, 4.2L
5speed
K&N air filter
3" intake mod
16" perma cool electric fan
Jacobs DIS
best 1/4 mile: 17.1 @ 81.53 MPH
total MPG average to date 19.15

My Second (but most important) Baby:
Hailey Jean, born April 9, 2000

 

yeah that does seem awefully high. i drive my truck almost exclusively highway and only get 13.6mpg. i splurged for 89 octane a couple of weeks ago and checked it the next time and i got 14.66mpg on that tank. i couldnt beleive it. so i filled up again with 89 and sure enough got 14.6mpg. i am not gonna try 94 octane though because no matter what mileage i would get with it wouldnt compensate for the horrendous price.

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1998 xlt off road 5.4lsupercab auto pacific green clearcoat power drivers seat, keyless remote with factory alarm, tow package

2001 yamaha 660r raptor 4 wheeler

 

I been keeping track of mine as well and I'm getting around 19.4mpg on the Interstate at 65-70 mph and overall around 15.5 mpg (gotta shoot the loop on the weekends)

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'97 F-150 XLT Supercab 4x4 ORP
Project "Hidden Horses"
4.6L v8 w/ auto & 3.55 LS rear end
Superchip!
AirForce 1 FIPK
Accel Coils and Super Stock Plug Wires
Crown Vic Police Interceptor electric fan system
Glasspack exhaust
Custom Graphics
Hard Tonneau Cover
GTS Headlight Covers
GTS Tailblazers II tail light covers
Cobra 29 NW ST CB Radio
Pioneer DEH-P7200 "Dolphin" Stereo
*current 0-60 13.5s & 1/4 mi around 70mph* (ouch!)

New Tires and dual Ravin exhaust next....

 

the only way you can claim these higher mileage figures is over the long term . . . there are definitely differences in "fill" depending on how the truck is "sitting" at the gas station. i know for a fact that the amount you can get in can vary by at least a gallon . . . that makes a huge difference in your mileage calculation . . . and it gets even worse if you did not run a full tank through . .

 

well i hope you guys are right on higher mileage cause the first three tanks i've got have been 12.9--13.1--13.1 fourth tank fill up today at 1738 miles--hope after break in will get better--course with mods i've got i guess i might as well forget mileage. all city driving no hwy.

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2001 F-150 4X4 Supercab
XLT 139" WB style side
5.4L V8 3.55 LIMITED SLIP AXLE
MODS:
AIRAID FIPK
SUPERCHIP(FLIP CHIP)
ROLL & LOCK TONNEAU

sitting in garage mods
GIBSON CAT BACK
GIBSON HEADER
REFLEXX COBRA HOOD
STREET SCENE GRILL
HOLLEY THUNDER SUPERCHARGE
ALL TO BE INSTALLED IN 20 DAYS