I've mainly driven mine since buying in Jan 20 on highway road trips to my kids 300 miles away. Early on it was 20-21 mpg. Now it's 22+ and my last trip back home was 24 with the AC running. Keep in mind I drive the speed limit, 60-70 and am a self described as SSSSSmooth (other say slow). I added a camper top at some point and I seriously think it helped the MPG. This is on a 2020 Silverado HC, CC, 6.5" bed and Max tow pkg-3.42
Pretty dang amazing considering the power available