Dodge didn't have anything to do with the develpoment of that cummins engine.
THey were just the first (and only) pick builders to installthem as OEM equipment.
Dodge probibly did have their own settings for fuel to get the HP and TQ that they wanted.
Yes compared to a 400 small bolck, All Diesels do quite well on fuel.
(RVM#26) THE U-RV 94 F-700/24 foot U-haul box home built RV