FWIW my mileage is still poor. The best ive gotten was a 50 mile round trip on the highway 14 mpg down with 19 mpg back 30 mph head wind down 30 mph tail wind home gusting to 50.
Other than that my average is still a lifetime of 11 mpg at 702 total miles. Mostly city driving. I have a 6 mile drive to work. I don't drive like an idiot...I've been driving to get good gas mileage. Mine will be going into the dealer next week. Bash me if you want...I'll post dic pictures this week...fact is my 2014 truck gets worse gas mileage than my 2012. My 2012 would get 13 with the same city driving conditions.
2014 Sierra All Terrain Crew Cab, 5.3l, 3.42, 18" factory Goodyear