Better Gas Milage and Shift Lock on e-350 based RV?

The best MPG I ever got was when the Cambria is parked next to the barn but that's no fun. Before adding on ALL the items that MAY squeeze some more MPG out of the beast I would total up their

cost and see how long it would take to cover that cost in fuel savings. A man at work traded in his full size pick up for a smaller one. We calculated all the costs involved and in 6 years he would start to see

some of his investment realized. Just drive the thing. A class C gets maybe 10 downhill and usually 7 to 9.