The newer DPF with DEF get better mileage than the older DPF truck with out DEF. Ofcousre the older non DPF trucks get better mileage than the DPF& DEF trucks for sure. I had a 07 LBZ that got very good mileage. One of my camping buddies had a 09 F-250 6.4 that got very poor mileage but Ford updated the program and mileage did improve some. I bought a 2012 F-250 Sept. 2012 and after he rode with me a few times and saw what the mileage was he traded trucks a few months later. Granted the computer mileage if off from hand calculated by 1.0 mpg high from what I have seen so far. My friend tells me his new truck gets around 3-4 mpg better than his old truck. Which most of the time mine gets 14-16 mpg rural driving and 17-19 highway running 70-72 mph.
I don't know if Ford or Ram'S method is better but the changes from their older design far as mileage goes seems better than what they had before. This is my first Powerstroke so only time will tell if I buy another down the road. However I still wish a lot of days I still had my old LBZ back. From what I have read and talking with other owners this DPF and DEF stuff has hurt all diesels no matter what brand. I currently have around 19k miles on mine so it's just breaking in good.
I was trying to offend in anyway just wanting to exchange some info.
