I am just really suprised, I expected this thing to get like 20-21 or so on the highway. Hell my old 03 5.3 ECSB Z71 got 19-20mpg on the highway with a 3.73 rear and without the fancy new VVT and whatever else they have now.

 

My dad purchased a 07 5.3 CC 2wd 3.73 w/ factory 20's and he is getting around 18-19 mixed city/hwy. He let me drive it and it drove smooth and very nice. However the PE delay and TM is rediculus, however he wont let me tune it. OH and it seems like your 5 ft off the ground they sit so high.

 

He got about the same MPG in his 05 Extended cab 5.3 2wd 3.73, but he even says that his stock 05 would walk all over his new 07...