Now that's timing, I made a roundtrip to Bend OR today with Elevation swing of over 4,000ft up then back down. I have AFM turned off so V8 100%, cruised around 75-80 except some traffic spots and got 25.7mpg. Last trip was 26.9mpg on my 2018 Yukon Denali 6.2L 10 speed with 86K miles on it.