Is This Right
 

i took a trip this week in my new to me duramax, all i have is a hypertech and I only got 15 mpg. everything is stock, the dealer told me i would get almost 25 mpg.

this does not seem right, maybe it is right but is seem low.

I used to get about 16.7 in my LB7 but that was with 35's and a 6"lift. I have "heard" that people get 22 but I never saw it myself.

what was your hypertech set on?

Is this like a short road trip or longer one? I see about 21-22 on the highway with mine.