My mileage is all over the spectrum :

http://spreadsheets.google.com/pub?k...JDJqjK_DrzwCRw

Its been fairly steady since October of last year, but thats because I don't tow during the winter. I'm not sure if I'm out of the break in period, still. Time will tell, I guess.

 

We now have 5504 on truck and on the trip up to Maine from Fl we averaged 10.5 to 11.6 mpg towing our 5th wheel trailer (Trlr wt 16,000 lbs) just love the tow command and exhaust brake on I-77 thru Fancy Gap and then on up I-81 and I-84. Truck worked great no problems. Fuel cost $905 for 2405 miles. Prices varied from $3.97 to $4.43. Just fueled up and price jumped to $4.89. We are now in Eastport, Maine for the summer. Nice and cool sweatshirt weather. Without trailer mpg is now hand cal at 17 mpg.

 

10 - 12 is about all I get pulling my camper at 65+ MPH, now get it down to about 55 and I got 13 pulling to Gatlinburg, TN and back from Greenville, SC. Pulling campers there is a huge amount of air being pushed, and air pushes back!

 

I am about to change my Errrrl. (Oil.) With Amsoil. Hopefully the synthetic will give me a mpg on the way up to minnesota. Once I get out of Central Tex-*** out of the hills, I should be ok. I am shooting for 18 mpg.

 

Mine seemed to start changing the most when I started pulling the boat behind it, seemed like every time I unhooked the boat the milage was a little better. With 28000 on the odo and the banks on 40 horse I get 20 to 21 at 75 18 with the boat at 70.

 

Well I wonder about mine I have a 2006 5.9L 4x2 almost stock, no engine mods only a leveling kit in the front and a leer shell on the back for my 3 dogs. On my trip computer in the truck on the flat Nor-Cal roads of the central valley at 60mph with cruise control set that little read out says over 26+ MPG. Now if I slowdown to 55mph it increases to over 29MPG and at 65 it goes down to around 25MPG. Now itsnot an average of city and highway driving when I figure that out at the pump I average around 18 to 22 MPG depending if I'm driving or my wife is driving (hers tenads to be a bit lower). The truck just hit 36,000mi and now I can't afford the $5+ fuel prices so she just sits in the driveway unless I have to take it to work so she can use the car. I know that little trip computer is not 100% accurate, ut how far off is it? I can drive from my house in Nor-Cal to the in-laws in So-Cal (about 450 miles) on just over half a tank, it usually sits between 3/8 and 1/2 and thats driving I-5 at 70mph. I gotta figure on a full tank I should beable to squeeze close to 750miles out of it. Anyone else doing anything close to that?