2019 GM trucks get smarter fuel-saving cylinder deactivation

mkirsch wrote:
My 2015 4x4 with 5.3L and 3.08 axle ratio gets slightly better fuel mileage than my old 2003 2WD with 4.8L and 3.42 axle ratio.

Clearly they have made some improvements.

That 3.08 coupled to the newer narrow ratio 6-spd vs a 3.42 coupled to the older wide ratio 4-spd is the improvement, not it's fuel management system. Your 5.3L also isn't working as hard as the 4.8L, especially under heavy load. :p