I now have over 5000 miles on my 2008 SCrew 4wd w/5.4L. The mileage I have tried to ignore, as it hasn't been good, but around town lately it seems a bit higher.

I just took a two day trip to visit relatives, and over the 582.5 miles of the trip [all freeway, elevation changes of 3600 feet up and back down, good weather, 55 mph on cruisecontrol the whole way] I averaged 20.7 mpg.

I now know that I can get good mileage if I sacrifice speed and A.C. It was boring, but an interesting experiment. Cruisecontrol on the whole way at 55 was a bit boring though.

Next experiment is to do the same route an keep the mph set at 65 to clock the difference at the pump!

 

I don't like to call out mistakes.... but unless you drive a GM, you have a 5.4 not a 5.3. I guess there is no way to point that out without looking like a *****.
That is some good mileage though.

 

Yeah I have noticed our trucks do much better MPG wise at lower speeds, I suspect @ 65 you will see around 18.5-19.0,MPG over 70mph avg about 17.5 MPG, its the tank like aero dynamics...YMMV

 

do u got any mods?
'cause sounds like a good MPG

 

Good catch, you're right. I don't drive a GM.

As for mods, the only things I've done are add a shell/cap [about 6" higher than the roofline too] from SnugTop, add step bars and a bug deflector to the hood. So, no mods that are designed to improve MPG or HP.

Someday I may do intake/tuner/exhaust, but now it is stock. Including stock American General 17" tires. Oh, and it has a 3.73 [?] rear LS differential too.

I was hoping 65 would be around 18 mpg. I'd be happy if 70 mph is near 17. I didn't buy this for gas mileage, but to haul stuff and people. I am just happy to get better mileage than I had initialy thought I'd get.

 

I have a Gryphon and on my highway trips I've taken I've gotten around 20-21 keeping cruise on around 67-68, around town any where between 14-16 if I can keep it around 30-35 and not too much stop and go.

 

Mavrik2747, are we talking 2wd or 4wd? tiresize? Rear diff ratio? I see you have the 5.4, I assume it is auto and not manual, right? Lift-kit?

I'm just trying to get an 'apples to apples' idea of if your setup would help me in the future.

Good MPG though!