the new diesels do have a lot more emissions on them for sure. the def is just part of it. I work on a bunch of Mercedes sprinters and they are not cheep to repair, or maintain. Some if they sense any sort of problem they go into a derate mode (limp) and you may get 20mph out of it if your lucky, other have to be put into regen mode to burn out the cat which can take over an hour to run. I have been thinking of pulling out the 460ci in our motorhome and putting in a pre 1980s diesel without all the emissions on it .. some places can also do some of the emission deletes as well to remove the DEF and the EGR that causes some of the unwanted engine shut downs..