Gas mileage

Adding a compact size toad load and filling the empty spaces in the coach moderately , one can realize easily a 25 percent increases in total weight while still being well within the Vehicles GVWR..... That's a substantial increase in load which can easily be calculated directly to fuel consumption and economy. In short, mathematically speaking , Weight is a huge factor that can be directly related to fuel consumption. Much more significant than vehicle aerodynamics all things being equally considered and calculated. In laymen's terms, my diesel Chevy gets 15 MPG unburdened, add a trailer and a 5 ton dozer , and low and behold it gets about 6 Mph....the aerodynamics of the truck itself remains unchanged. Weight is the biggest factor in gas mileage with these moving billboards. Look at the major auto manufacturers and their Engr., solution to mandated government fuel mileage ratings are reducing weight above any other Engr. principal.
My educated 2 cents.....:B