I know stay off pedal, but what is the best anybody has gotten and what did you or they do.

The best mileage accessory I can think of is to buy a smaller truck for most trips and park the dmax... If the tires aren't turning, then you aren't burning fuel.

seriously though, my Edge added about 1 to 1 1/2 MPG on lvl 2, but really required discipline on driving habits or that goes right out the window.