I have a ‘15 Tahoe with the 5.3 and just did a 1300 mile trip from Phoenix to southern Cal and back. I drove exactly the speed limit everywhere and got 23.5 mpg, which is about 625 miles per tank.
The best I’ve ever gotten on mpg is 49 for 25 miles, 37 for 50, and 26.5 for 400. All while...