the milage is down some because of the DPF (diesel particulate filter) which wastes fuel to burn off soot but otherwise the engine itself wasnt really changed at all from the previous generation (LBZ) so i dont believe they are having any new problems. the fords and dodges are another story but those were both newly designed/redesigned engines.
oh, and good to see another western NY'er! welcome to FSC! im in Rochester.