I think that has more to do with the manifold you choose & any other mods, rather than it being a Sierra.oh okay I thought it was a good brand. I have heard with some truck brands you have to get a custom tune with an intake is this true for sierra's? I know it would help even more but i have a small budget
Seems like the Smart Car is the way to go.
The webmaster of this site, Steve, has been pushing for these since last year.
Way better mileage than the 2500HD.