docdvm wrote:
I bought a 2017 Ram 2500 with the Cummins 6.7 Diesel. Previously had 2 Ford F150 ecoboost. I am getting better mpg from the Ram even though it is not yet broken in. The DEF fluid lasts a long time and has a gauge so you know when to pick up some more. I really like this truck but have not towed with it yet. Daily driver for now.
I find that DEF usage is based on the amount throttle you need apply to hold speed and how much temperature the engine is currently creating. If you're driving unload in cool weather on flats with a tail wind, DEF usage seems to be minimal. If you towing a heavy load on a hot day over steep grades or fighting a headwind, the system has much more thirst for that DEF to keep NOx emissions down.