I have an 07 4X4 long bed extended cab. I have no problem breaking 20MPG on the hiway as long as I don't go over 70. Over 70 and it does get hungry. Running around town I get 15. That is by the computer and I hear they can be happy to the tune of around 1MPG. Never checked it manually.

your 1st post says you just bought a 6.0. my question is why? did you read all the posts that talk about all the problems? im a car / truck dealer we wont even take them on trade. do the egr delete and the oil cooler before they go bad, take the tuner out and go back to stock,and keep your fingers crossed.there is complete fixs to the 6.0 issues go to the diesel stop.com there is a whole section on 6.0s . I know there is 6.0 lovers here ,but mine left me on the side of the road to many times for me. I bought a 650 with the cat it got around 16 on hwy. over 10 towing the boat at over 70, hard to check it holds 80 gallons, I can leave chicago full and go to lake of the ozarks ,run around all week and come part way back with out stopping for fuel

I haven't owned a Ford diesel in 20 years(6.9L) but with both my Dodge diesels if I ran them over 2000rpms the mileage would nosedive. Are the Powerstrokes the same?

hand calc. I just have an XLT, so no lie-o-meter.
For the other guy...I have the sinister egr delete. It was kinda a pain in the ass to put on, just gets old laying on top of the engine. I think I have a permanent hood latch imprint on my gut.

My 05 Dual wheel with 22.5's gets a lucky 13mpg on a good day with exhaust and air intake. I put a Bully Dog E3 programmer in it and the next week the fuel injection control mod went bad so I ditched the programmer. I drive my duramax and get 21 ALL THE TIME towing or not. Hate the chevy but tough to beat the power and reliability.

if you work on truxks like i do you need one of thease,worth every penny!

http://www.nomadmfg.com/