I have a 2020 Silverado with the 3.0 Duramax. About 12000 miles on it now. In mixed driving, I average about 23.5 mpg. My commute is about 250 miles per week of 75% highway and 25% city driving. On pure highway trips, it averages between 25-32 mpg, depending on wind, speed etc. I have larger than factory AT tires, so I imagine that will cut into mileage a bit as well. For my driving style, I really love the 3.0 Duramax. I don't have a heavy foot and I like it better than the 5.3 V-8 that I have had in the past.
