My 2006 silverado 4x4 5.3 gets 18-19 mpg in town all the time , but never do much highway driving, but when i do i reset my digital average mpg gauge on the gauge cluster and when going 60-65 mph i it says 22.5 -23.5 mpg. just wondering if i can believe that digital mpg gauge. But i have figured my in town driving the old fashioned way with a calculator and usually always 18 or better , and that is what my gauge says. let me know thanx

 

Well I have a 2004 with that computer MPG stuff. Around town I do not beleive it, becaue it is normally a half a mile to two miles off. However on the freeway it is pretty right on, but only if it is strictly highway driving.I drove a 2005 Chevy to Nebraska and it got 22 MPG as I recalled. The biggest difference in my 04 and the 05 and up is there is less Bullshirt. Meaning my coputer reading stuff is like buying a preloaded computer system. It has too much BS. So what I figure is as time has went by they streamlined the system and made it more accurate. I personally trust the old school way of checking my mileage.

 

just did an average of 2 tanks 80% city and got 15.9 mpg

 

I have a 2008 silverado. The computer gives you an average mpg. In other words, if in the city your mpg is 16 and on the highway 24, your average is 20 mpg. You are never told the actual trip mpg. When I go on a trip, I figure mpg for the trip the old fashioned way by dividing miles driven by gallons used. An example is 400 miles divided by 20 gallons = 20 mpg.

 

I bet your intake is pulling to much heat from under the hood. How big are you duals? If yuor duals were 2" or so each and you had a modified intake to pull colder air from outside the engine bay, you would get 18 or better MPG.

 

the intake pulls most of the air from the factory hole in the bottom of the engine compartment. not alot of enigine heat is getting in there. as for my exhaust its all factory except the single in dual out 40 series flowmaster.

the truck has 3.42 gears and where i live its right hilly so that is killing the mpg. also i rarely drive on the highway. not helping either.

 

hate to say it but unless you personally re geared your pickup, its not a vortec max, they only came with 4.10 gears, and they were not available in the Z71 package for 2006.

mike

 

That sounds right. My highway mileage is now about 25 with the LS1 cam and tune. 19 in town.

 

Dude, that post was July of 2008, i had an ext z71 with a 5.3. then in august 2008 i bought my vortec max.

Nice thread dig though.