My owners manual states if you are towing use tow haul. I did on our last trip and noticed a big difference in gas mileage(lower) than when I was not towing. I am going to try and only use it on hills up and down next time to see how that is. I don't really know if you need it on the flats as much, maybe someone else knows as I have only had mine for 8-9 months now
2015 Winnebago Forza 34T
pushed by a 2011 Fusion Hybrid or 2020 Escape Hybrid
Retired DFD