I drove about 65 miles on interstate about 70-75. The rest was rural highway going about 60-ish

 

being a 4x4 does not have any true affect on MPG...it's all about the driver and the gas quality. I regularly get the same MPG as 2wd guys and I don't baby my truck.

1. did you use E-85?
2. slow down. your mpg lowers big time once you go over 70 mph. try going 60-65 and you'll be amazed
3. keep her under 2000 rpm
4. reset your odometer when you fill up. then divide that reading by the gallons of gas you replaced when next fillup occurs. the only method to read MPG
5. avoid jackrabbit starts and stops
6. CRUISE CONTROL

I get 16-20+ mpg on the highway...just depends how fast I go vs. how many MPG I want.

City is 14-16 mpg consistently

 

All;

Firm up those big tires (even the stockers) on the highway and you will see an improvement. I tried it on a long trip (madison to twin cities) and got almost 2 mpg better with my stock 18"ers at 48psi. Ride is a bit stiff but no too bad. the tires are rated for 50 max so no problem there. Just dont expect them to be great in the field without softening them up a bit.

BJ

 

When I drive my truck I love to hear the glorious sound of my Magnaflow cat-back so I don't even want to know what my gas mileage is........

 

Seems to me that if 4x4 robbing 5 - 7% of my horse power it's gotta be taking 5 - 7% more fuel? Maybe I'm tripp'n.

Are you running a tuner Tylus?

 

I'm in the same boat as you. SuperCrew 4X4 with stock tires and a 3.73 rear end. On level ground no wind going 75 I get 13.7 MPG. I drove 330 miles on Monday and started out getting 15 but then it dropped off to an average of 13.5 by the end of the trip. It was pretty hilly on Monday, but I still think I should get at least 15mpg on the highway.

 

Since I've had my truck back I've been getting 13.4 mpg on 37s.

 

Im gettin 14-16 city and 15-18 highway and thats with 305/35/24's pumped up to 50 psi just keep the cruise on up around 65-70 and thats that. when purchasing the truck you knew you werent buying some 4cyl 1800LB car its a truck that weighs in @6k

 

Yeah I hear ya , but now it's more of a chalenge to match some of these guys getting 18 - 20 mpg with the 5.4 3v. I think I might start a post for just 4x4's with the 5.4 and see what the outcome is.

 

Wind and speed has a great deal of effect on my milage.

On flat terrain with no wind I get 15mpg at 70mph and 18mpg at 55mph.
With gas prices my truck hasn't seen faster than 55 in two weeks. lol
runs about 1500rpm at 55mph and 2000rpm at 70mph. 40psi in the tires.

However I had to drive into a 30 mph wind Monday for about an hour. With that I got 14mpg driving at 55mph.

 

with 5.4 and 3.55 gears and stock tires was 14.7 and most recently 15.07 mpg in city driving.It has close to 2,500 miles on it i have noticed it has picked up on mileage since it got warmer here in Northeast,Ohio.

Later Mark.

 

how is it robbing 5-7% of your HP? you and I have the same transmission (if 5.4 anyways)...the only "drivetrain" difference other than wieght is the transfercase. and it's not spinning all of its components unless in 4x4. only the input shaft and the output shaft are rotating while in 4x2. the 4x4 weighs about 250-350 lbs more, but that is sprung wieght, not rotational weight (front axle and hubs don't rotate unless in 4x4). a 4x2 with a toolbox in the bed and some tools will weigh in close to a 4x4 empty.

nope, no tuner, just CAI and catback duals. stock 275x65x18 rims/tires

I just use cruise everywhere I can, I use good gas, not the cheapest I can find, and regular oil changes. I'm fairly light on the pedal, but I nail the throttle at least 1 time every time I drive it (I love to hear my magnaflows roar). I do try to minimize my time above 2000 rpm, but sometimes I can't help it.

like I said, I get 14-16 city MPG, and 16-20+ highway mpg. When I drove from Seattle to Austin in February, I got a best of 21 mpg and a worst of 13 mpg...the mountains made my MPG suck, but the flatlands (KS, OK, TX) made my MPG go right up. That was also going 70-75 mph on cruise with 500lbs in the bed and my wife and daughter in the truck

I think my tank right now is about 14 mpg...I've been having some fun with all the pretty weather my area has finally gotten.

edit: oh yeah, I've got the 3.73LS...IMO, the 3.55 shouldn't be an option. it has a minimal effect on MPG and with our trucks being so freakin' heavy, the deeper the gear, the better. 1750-1800 rpm at 65 mph, 1900-200 rpm at 70 mph...ain't bad

 

Not sure how it does it , but the place I had it dyno'd mentioned it right up front and even printed it on the sheet. I think I read it on here somewhere. Sounded resonable to me .

 

2005 Screw, 4.6L, 3.55ls..

stock I never got better than 17.4 mpg highway usually at 80 mph.. after I put on the borla cat-back I get 19.21 - 19.27... I don't think anything makes a hell of a lot of difference with these trucks in city driving, if I get 12 mpg I'm happy..

 

I have the '06 XLT scab 4x4 3:55LS and just checked my mileage for the first time. I drove 575 miles and when I filled up it took 33.8 gallons. That = 17.01 MPG. About 300 of those miles were highway going between 75 and 80 MPH w/no cruise control. The rest was in town with fast starts and stop and go traffic. That turned out to be better than I thought The only thing I have done to it is a Corsa catback. Still waiting for tunes from TP so I can hook up the intake. Interesting to see if it makes a diffrence.