Another way to get a vehichle to move a bit quicker with less throttle is to lower the rear gear ratio.
This creates mechanical torque mutiplication to move the weight with less effort.
Problem is at road speeds the motor will turn a higher RPM so again there is a compromise between rpm and less throttle that may or may not result in sleightly better fuel mileage, depending on the driver.
The point that the least amount of throttle opening is needed to maintain the desired speed is the best that can be done.
After that, the weight has to be reduced, the engine compression would have to be increased, best fuel used, drive train losses minimized and on and on.
An owner cannot re-engineer to those degrees without expending a lot of money and test time to arrive at a gain of a few percent in mileage that may cost thousands to accomplish.
Be assured the factory would get the mileage if it were that easy to do.
Notice that even today the mileage is still not that much higher with the new trucks.
Changing air intake, headers and custom programming could result in about a 40 hp gain but if your after fuel mileage, power is not the only thing your after. It's efficiency.
Again the only way is to lighten up the weight and burn the fuel more efficiently. A rise in compression gains efficiency in all rpm ranges but other factors come into play to limit how far this can be taken with the cost and the fuels available.
It makes no sense to spend hundreds on an air intake system and filter that can makes no improvement at low rpm where the stock hardware flows well more than enough air.
It takes at least 10 hp to be felt by the seat of the pants dyno so most mod attempts never attain the min of 10 hp to be close to effective and worthwhile.
Want the best fuel mileage, get a short wheel base 2w drive and lighen it up as much as you can, if you still want a truck you can haul some with.
That's why small cars with little motors get the big mileage number.

 

to my knowledge they are no longer required to tell you the amount of ethanol in the gas therefore most places you get gas have atleast 10% ethanol now and dont disclose it. they make gas cheaper that way and make more money that way and you can thank the greenies for worse gas mileage

Correct me if Im wrong

 

there is a website here http://pure-gas.org/ they have state listing of pure gas..

 

Yea, I knew of one station that was E free. Thanks for that site jethat...I just learned of a couple more! I think I may try a tank of E free next just to see. COMMON Sense would dictate that I'd HAVE to see an increase going from ethanol to ethanol free...all other things being equal--DirtySCREW

 

Dirty the E- free might help.. Also are you running over size tires?

 

i only run ethanol free now. i get noticeably better mileage with it

 

NEGATIVE...I'm running STOCK size tires (265/70R17) but they are BFG ATs. So I know I have a slightly more aggressive tread pattern, but it shouldn't take away 2 or 3 mpgs. Cause there are member on here that HAVE oversize tires / lift and are getting better MPGs.----DirtySCREW

 

03 F150 FX4 Screw with 33" MT's 5.4L 3:73 gears K&N drop in flowmater exhaust and drive 70 everywhere(almost) mixed driving and get 14 mpgs consistanly. Have seen up to 16 mpgs tho on strictly highway at 60 mph.

 

Yea, that's factory for the XLT Off-road tow package. Don't believe everything you read lol.

 

Well dirty i am filling up prob before thanksgiving ill let you know my avg.

 

So what are you getting now DirtySCREW - I may have missed it.

 

I went up in tire size and have been getting slightly better mileage. But I also only went from 235/70-17 to 265/70-17 for Cooper Discoverer ATRs which are actually lighter than I expected for an all terrain. Around 45-55 I can get awesome mileage. The programmer says the average is up to 24, and I can keep it there for over 30 miles, but it can also be off about 1-1.5 mpg. I dont drive those routes enough to have an accurate hand calculation.

 

Jbrew---I can't say. I had the "accident" with the truck and I refilled to get a more accurate average. I'm still above 3/4 a tank right now with Eighty-something miles on the tripometer so far that was highway. I'll let you know when I fill up again, but it will probably be a few days after Turkey Day.---DirtySCREW

 

Oh yea, that's right, - your front end took a soil sample. Forgot about that lol.

 

well i just did my MPG from a recent trip, about %85 highway, and got 14MPG. yikes, but whats to be expected from a 5.4 with 175k miles, 4x4, heavy bumper and 285/75/16's. hopefully the e-fan will help. also considering seafoaming it