We are currently on a trip to Colorado with our 22 Yukon SLT 4wd with Max Tow and 5.3 currently with 1900 miles on it. Left Phoenix, AZ and headed to Payson, AZ then to Gallup, NM then to Shiprock, NM, up to Del Norte, CO, Fairplay, CO and into Littleton, CO via CO-285 so a lot of twisty road and high mountain passes and have averaged 13.5 mpg towing a 3500 pound trailer, so pretty happy with that as my 2015 Yukon 5.3 did about the same. The 10 speed works great towing better than the 2015 6 speed did. Love the way it tows! Getting used to the electronic shift when going into low. One thing I don't care for is that there is no way to run the Yukon in normal driving mode as it always defaults to tow haul mode when the trailer is connected as we almost always towed the trailer in normal mode with the 2015 and had no issues and a little better mileage that way. The other issue is hooking up the trailer as the parking brake tends to move the Yukon 2-3 inches when I place the trailer tongue over the ball which makes it very difficult. Unless I am doing something wrong with the park brake (not the P button with the other forward & reverse). Other than that this truck is a beast of a tow vehicle and very happy with it.