What a free for all! I'm a 24 valve running 3:54, stock tires, and an edge comp. I see about 20-21 highway, driving 65-70 in the mountains (hand calc) and I can squeeze out 24mpg if I drive under 62, and really watch how I treat the $ petal. As a former truck driver I can tell you that your driving style is somewhere over 30% in the factoring for your mileage. Don't floor it, let things wind up as you add fuel, and keep your lead foot off the gas and you will get much better mileage. Want more statistics? Go to OOIDA's web page--www.landlinenow.com--and read some of the articles in Land Line Now about fuel mileage. OTR Drivers in the same truck with different driving styles can vary from 2-3 mpg. In my case I could squeeze out 7mpg from an 08 pete with a 475 hp 15 litre Cummins ISX, and my boss could only get 6 out of it. We both averaged 67mph on the computer when we downloaded it and both pulled loads of comparable weight.
Guess what I'm trying to say, is change the way you drive, then check your mpg and see if it helped. No help, change again, et cetera.
And I do have to agree, for 7K+ trucks we see darn good fuel mileage!

 

i understand that if i was running 80 it will not be that good with 4.10's but i'm talkinabout 55mph.easing around.

 

ok to get the best MPG's try and keep the boost as low as you can. that boost guage should stay either on 0 or darn close to it unless you hit a hill and 5 -6 psi should get you up any hill unloaded. another thing is keep your speed the same set a target speed and just keep it there. just a few tips

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and fyi stock 06 cummins 17 city and 13.5 towing with an auto

 

 

change the fuel filters , change the tranny fluid ,change the rear differential fluid, proper tire pressure

 

You see this statement of 55 was not mentioned in his first post so this will cause you to think what is he doing or how is his truck tuned.

I personally get about 18.5 mpg running 65 with a cheap set of 265 tires. I have my fuel plate set on the conservative side because I am more concerned about egt's while pulling my trailers than I am about HP, sled pulling or racing. I agree with what others have said about how you approach the speed you want to drive at get there in hurry fuel mileage drops take your time fuel mileage is more stable. I use to get 19 to 20 when my truck was stock but the diesel fuel was a whole lot better then compared to now.

 

thanks guys! i am trying the whole changing my driving style, and we will see what that gets use! thanks!!