Don't want to piss anyone off, but diesels getting crazy high gas mileage does not happen either. Yes they do get better than gas. Too many guys use the overhead lie-o meter. Everyone needs to get out the pencil and paper and come back to reality.
True. Those things are a POS. Don't go by the Manufactures Sticker either.
My Excursion gets 980 Miles per tank / 44 Gallons at fill up = 22.272 MPG
It would probably pull 3 or 4 Gas burners behind it and get the same and not wind up or slow down going up the grades.