Useless Information

[Marky Dissod]

... back in 2018 I looked at the fuel economy of our actual trucks (Fuelly.com and window stickers) and saw that there was virtually no difference between the 2007-2008s with their 4-speeds and the 2009 with the 6-speed.

Check more closely. 6L80 trucks typically came with 3.08 axle gear. 4L60 trucks typically came with 3.73.
If more 6L80 trucks came with 3.42 (tow pack) or 3.73 (better tow pack), that'd've improved metro / urban MpG.

I've nothing against VVT - GM should've implemented that sooner.