I seem to be getting horrible mileage, maybe average of 12mpg? This is like my dads 460 F250 was?? WTF? AEM intake/Predator/MBRP exhaust are the only mods. I tuned the truck myself, fuel trims are right on, no clue why the the mileage sucks so bad. I'm going to change the fuel filter asap when I do the oil. My trip to work is 1/2 highway and 1/2 rural roads about 15 miles one way.

 

on my trip to calgary i was avg. about 16 mpg. all i have on the truck is a k&N intake and mrbp exhaust. No tuner at the time. Also i have 35" bfg mudders so that probably sucked my mpg down a little.

 

I might stick the stock airbox back on and flash it back to stock and see what happens.

 

My experience is different engines and driving habits play into it MORE than people think. In town, start and stop is the worst. A/C on, jack rabbit starts. It all adds up. Exhaust and CAI are good at highway speeds but I can believe they make any diff. town drivng.

Everyone was shocked when all I could get out of my 4.2L was 10-12mpg. The best I ever got was 13.3mpg one time.

My new line is...
No one buys a truck for gas mileage. If you want mileage buy an economy car.

 

That sucks, I get 20 on the hwy at 55-60 mph its all how you drive it.

 

When I first got my early 05, 5.4, 3.55 rear, XLT Screw, I got 16.8 running around and 19.2 on the highway. With all my mods and the 10% ethanol, I am down to 15.5 and 17.

 

In mechanics school one of our instructors had a little half gallon set up that was fairly easy to connect to any car and be able to see inside the vehicle while driving. We would go out with people and tell them to drive normal. It is shocking to see how "normal" driving eats up a half gallon of gasoline. People just do not realize things like that until they SEE IT with their own eyes.

He also told us if we wanted the best mileage the car could do was to ALWAYS drive like there was an egg under the accelerator...LITERALLY! Drive like a grandma.

Ethanol is a BIG killer of mileage.

 

I get 18.5 on my 04 xlt no mods at all,is 37 miles one way half highway half rural

 

Ha I got 12.4 last tank but thats because it was new so I was flooring it all over the place. With the 3.73 LS rear end and 275/65/18 tires.

 

15-16 since I bought the truck in November. Mainly city.

 

Do need to know your rear end ratio too. I see only one post referencing it and its its also important to know.

 

14-15 in the rural area I live, about the same on the highway with edge, s&b intake, flowmaster exhaust on 35 mud grapplers. I can light foot it and get 16-17mpg.

 

i got 13.8 city my last tank, i have the 4.6 tho. i have 35s a tuner intake and exhaust. usually get 15.5-16 highway going 70 or so mph.

 

I average 14.5-15 mpg virtually every single tank, thats roughly a 50/50 or 60/40 split (hwy/city). I have seen as high as 19.7 (on stock tires) and 19.3 (on 325/60/18), on a long highway trip with cruise set at 60mph. And as low as 9.2 or 9.3 (if I recall correctly) this was alot of towing 6-9K loads.

My truck is a 04, 5.4L, 3.73 gears, Edge Evo on lvl2 running 89oct, Airaid Jr intake, custom 3" exhaust, 325/60/18's on 18X9s (spring/summer/fall) and stock 275/65/18's (for winter)

 

I get around 14.5-15 around town, but my trips are short, usually only 3-4 miles one way. I drive very smooth and no fast starts... my mpg would probably be a bit higher for longer trips.