I just came back from a 2 1/2 day trip from Virginia to Arizona, (one that I made a few months back from AZ to VA) and on both trips I only averaged 10 to 12 MPG on the highway of course. My average speed was 80 MPH and I have a K&N drop in air filter. Shouldnt I get somewhat better mileage than that? Is there anything else (besides major mods) I can do to get better mileage? Something with the computer maybee? RV

 

You should be getting 15-18 (unless you are going uphill the entire time). You should take your truck in, a reflash may give you better MPG. You could also have an engine problem, I have heard that the O2 sensor can give poor MPG. You should definately have it checked out.

I get 15-18 on short highway driving, I would expect 18+ MPG on a long trip.

 

I did almost the same trip, NC to AZ, a few months back. The best I got was about 13.2 mpg. That was going 80+ the whole time with the A/C cranked. What route did you take? I went I-40 so there was a little of what I guess you could call mountain driving, i.e. through Flagstaff, Albequerque, NC/TN border.

 

Yeah, Ill take it in, itll have to wait till Saturday though. The dealership near my work closed so I have to go 25 miles the other way to get anything done.
THAYER: When I went to VA, I took 10,20,30,40 and 81. Most of which was pretty flat driving. This time, I had to go through Phoenix so I took 40 all the way to Flagstaff. Both times, mileage was pretty much the same. BTW, Texas SUCKS. And its not fun to drive through either.

 

Ive gotten as much as 20.5mpg on the hwy when completly stock with a drop-in K&N. Lately I have been only getting around 15-16 on the highway. Im pretty sure its the bigger tires I just put on. And yes I am taking into account the speedo is a little off. Its a big heavy truck. I guess you just deal with it or get a car.

 

My frequent Portland - Salt Lake City road trips usually end up being about 16mpg with the 5.4L doing 75-80.

 

these mpg numbers you guys are getting amaze me. What configuration are your trucks? Gearing,4x4,scab, etc...I see no where near the figures you guys are talking about.

Dan

 

I have an 03 stx with the 5.4 4x4 3.55 and crusie and get between 16-18 mpg highway. I have an k&n drop in and put a borla exhaust on it which gave me 2mpg over what i was getting stock.

vvyk3d as for our figures sounds like most are the 3.55. I had a 00 with 3.73 and was lucky to pass the gas station.

 

For whatever help this info is:

100% stock 4x4 Lariat SuperKrew, 5.4L w/3.73 rear end.
Based on the info center: 16-17.5 MPG
Have manually calculated as high as 18.3 MPG
Driving habit: easy accelerataion from all stops, lot of coasting to stops. Only "stomp it" once in while (or a Chevy is next to me).

 

Clean your MAF sensor with some electronic parts cleaner. The K&N filter was probalby over-oiled.

 

I get 16.5 mpg at 80 mph on highways w/hills using the k&n drop-in filter.

5.4 v8, 3.73 ls rear end, 4x4, supercab

 

17mpg's @ 80 (most of the time) on freeway trips only. 15 city/mixed.

Bone Stock.

 

That’s terrible gas mileage; there must be a tuning problem somewhere. I get 15.5 to 16 mpg local driving and when I hit the highway, it goes up to 17 plus. I do have a 2x4 with a 3:55 rear though, that accounts for a little better mpg.

 

OK...if yall are getting THAT kind of gas mileage...my truck must be a pos on wheels. i gotta 04 fx4 screw 5.4 w/ a 3.73 in the back, no performance parts. 30 gallon tank (normally get it to about 28 gal.) and i get a whopping average of 330 miles till i have to fill up again. i dont even stomp it(unless, yes, there are chevys/dodges at the stop light). still, i shouldnt be getting 11.5 mi/gal!!! i've noticed a lot of crap wrong with my truck though...something that...if i wasnt studyin or at work all the time...i can take it in for. lets see...truck bed vibration, steering wheel vibration, something that resembles a "cluck cluck" sound you would hear from a 200,000 mile engine, a loud knock below the passenger side of the cab at miscellaneous times (but most especially when i put it in gear at startup), a whine noise around 47 mi/h, i could prolly think of some more. would i be wrong to presume i should take the pos in asap?

 

My truck is exactly the same as yours. FX4, screw, 3.73, with the big tank. I get 450-470 miles on a tank.

Now with the 285s I get about 400-420 but then if I figure in the tire difference.... its only a little less.