Haven't really noticed any change. The truck isn't my daily driver and spends most of its time hooked to a trailer. Whether its my camper , dump trailer or my buddies bass boat. I have in the past averaged 15mpg around town and 18 on the highway. If you look at the Trip2 screen since day one i have averaged 14.4 mpg over 8000 miles but half of that was towing something..