[QUOTE=rowiebowie;138402]You have, by far, the most fuel efficient Promaster ever. Sure you don't mean 18-20 on flat highway? That would still be the most fuel efficiency I've seen for that model.
Yes I’m sure. After the one that is quoted above, I had a 2018, 159 inch wheelbase tall roof, and I consistently got 25 miles per gallon on the highway if I kept it under 65 MPH. Now I have a 2021 chassis manufactured RV on a 3500, 159 inch extended wheelbase… And my gross vehicle weight is about 8000 to 8300 pounds at all times, And I’ve got all sorts of crap on the roof including an air conditioner, 2 exhaust fans, Thule cargo racks, solar panels, plenty of exhaust tubes for the black tank and the gray tank, an awning that is in no way at all aerodynamic hanging off the side, and there’s even a Winegard antenna on top.… and at 65 MPH, I consistently get 22 miles per gallon. Even the trip computer for this RV, which I have never cleared, says my average is 21.2, and we all know how often they can be. I will admit, if you go more than 65 MOG, gas mile plummets into low teens.