Where at in Texas are you? I live just south of Houston and the gasoline that we have to use has that special blend which lowers fuel mileage and performance. My truck always runs better when I go out of town and get gas away from the Houston area.

 

08 Screw w/5.4L 3.55LS

City - 16
Mixed - 17.5
All hwy - 19.2

 

04 5.4L 4x4 3.55 gears, 35x12.50/17 rubber. Not a good combination mileage wise. When I upsized from 285/70R17s my city MPG went from about15.5 to, depending on how the right foot is applied, between 10, and 11.5.

I added a fully updated Xcalibrator2 that I got off of a colleague that recently sold his Mustang. I haven't had a full tank through it yet, and need to get back in and tweak a couple of parameters. (idle is too low, keeps throwing a code).

From the eyeball approach to the instrument cluster, If the gas gauge is right, it looks like I am back into the 15+ mpg city range.

 

I have been able to get 19-20MPG on a round trip to State College from south Jersey. I average about 14-15 around town but that drops when I am towing my trailer. I have an 07 SCREW 6.5 bed with 5.4...
Just put an Undercover tonneau on last month and will be taking a trip to Georgia for Turkey Day. I am wonder if the new cover will add any MPG on the highway... we will see....

 

Lubbock Tx, and we also have that 10% ethanol crap
I got my 22 mpg going to oklahoma on that stuff, and got 20 coming back at 73 into a headwind on the Oklahoma gas... dont know what it was though.

 

'06 SCREW 5.4L 325/60r20 3.73's. Haven't driven on the freeway yet, but around town (30 mph everywhere) i'm getting 11.2 avg. Reset everything and did a short trip on a 50 mph highway and got 13.6, but i was on it hard the entire time to see what kind of pickup and power it had, and I only did it one time, so the test probably isn't conclusive. Probably won't go on a 'freeway' drive until Christmas, when i do, i'll post those numbers.

 

2006 XLT 5.4 Scab 65-75 23 miles to work 23 miles back, I manage 17.9 almost every fill up.

oh yea, its a 6.5 bed.

 

What the hell am I doing wrong? I drive the same miles (really is 23 there and 23 back) and speeds to work and get 14-15 with the same truck. Almost all the driving I do is highway.

The best Ive ever gotten was 15.8 and the worst was mid 12's.

 

Gryphon is saying 17.3 over the last couple of tanks ?? Sounds pretty good to me

 

elevation? Tire size? gears? I do not have the 4:10 gears, I have 383 I think, I have the towing package but the higher gears.

235/70/17

I am in east Ky too so its not flat land.

Here is how I figure 17.9

I went X miles divide by gallons of gas, I normally get 17.9 some times as low as 17.

I suspect that my next tank well show less, with the town diriving I have been doing, and if I get a camera man, a burnout is in order before my new tires.

Strangly I can only get both wheels turning some times, hope i dont break my truck.

 

My truck is totally stock. I havent changed anything on it except for adding a reusable air filter.
235/75/17 tires, 3.55 gears and I figure out the mileage the same way (dont even have the miles to empty calculator thing).

Really I dont beat on it at all. I try not to let it hit above 2500 on the tach either.

 

12-13 town
15-16 highway

3:73 gears stock tire size

 

13-14

 

Little things can be done to help with mpg. I get city around 14-14.5 and highway is around 16.5-18.

 

The display reads 13.8 right now. That is city miles, from stop light to stop light with a little freeway. Slightly higher in summer, slightly lower in winter.

When I take a trip on the freeway it will jump right up to 17.