Had my 2019 AT4 with 6.2 since Sep 2019. Major reason for 6.2 was it was the only way to get 10 speed tranny on 2019 models. I had the 8 speed in my 2015 6.2 SLT..the tranny was crap, one of the many reasons I no heartburn with trading it.
I have just over 10k miles combination rural/city/highway. Getting average of 18-19 mpg. Get a little better with highway trips..20-22 mpg. 24.5 is best mpg I have gotten, but it doesn't take many hills to pull that average down.