I see most of the fellas at the site average a whole lot more MPG than I do. WT485SPDSilverado even said he got 22 mpg, in the city. Wow I guess somethings wrong with my truck. Its a rcsb 4x4 sierra with a lil 4.8 and i dont even get 16 mpg. The most i've ever gotten was 330 miles to the tank. Man that really sucks!!! Any suggestions on why I have such shity gas mileage. Hopefully when I do my 6.0 swap next week i'll see some improvements

 

The only mods to my truck are teh hypertech tunner, K&N kit,throttlebody spacer,and that is it. Would just these simple mods affect my MPG. Hahahah maybe I have a huge gas leak. lol I dunno somebody help

 

You Need To Get Mufflers To Let That Thing Breath

 

Don't hold your breath for better milage with the 6.0

I've got a NA 5.3 with 4.56s and 35" tires and I get close to 16 mpg. Not bad considering that's about what I got when I bought it new.

 

Oh yeah, I had a hypertech once and that POS dropped my mileage. Sell it on ebay while you still have a chance and get a real tune. I got about 3 mpg back when I did!

 

yeah hyper is a bunch of junk. gonna have to sell it

 

330 miles to a tank doesn't sound too low for a 4x4 truck, also the 4.8 doesn't get much better mileage than the 5.3. If someone is claiming to get 22 MPG in the city in one of these trucks then I've to to hit the

 

I got 19.1 on the hwy in my 04 crew cab 5.3 w 8psi STS kit and cam. I was very happy with that!!

 

I average mid 18s on mixed driving with over 400 miles a tank

 

Nah no BS here. I've got pretty much the same setup you do, cept not near the stuff done to it. My brothers 5.3 EC Z71 gets 18 mpg in the city. My truck has the smaller engine, a 5-speed, regular cab, 3.42's, CAI, no cats. 22 is regular, and it has touched 23. I start off in 2nd at most stops and shift at the latest 2000rpm, but most the time 1500rpm. and check out motor trend, they had a silverado w/345Hp gettin 25mpg.