My 2020 AT4 with 41k+ miles has a lifetime average of ~17.6mpg with several thousand of those miles having a trailer with my Can Am X3 on it. I dip to about 12-13mpg when towing and with just the truck, I'll get 19-22 in the warmer months. About 18 during the winter at best. My commute is about 30 minutes and is where I generally get 20mpg average.
Stock 20" wheels and OEM Bridgestone tires. Only thing added was a S&B CAI and it had little to no effect on my MPG, I just wanted to hear the engine without adding an obnoxious exhaust.