What can I do to improve Gas MPG on my 06 Denali.
I have a 06 Denali with a 5.3 and was wondering what to do to improve the MPGs. My wife drives it in the city everyday and the computer is saying 11 MPG. On vacation it got 20 plus on the Highway, just looking to improve it on the street. As of now it has 100,000 and is all stock, no Check Engine light and runs excellent. I have heard a CAI, different plugs, a tune. Just looking for what kind of improvements you guys are getting with any mods and is it worth it.. Thanks in Advance