I have a 2013 Passat TDI and have made what I think is an unusual observation. I think it has a fuel scheduling problem. It doesn’t manifest itself very often but it is noticeable when it does. On subsequent days (easier to see when it’s cold) the car will behave quite differently. On one day it will take its time warming up (typical) and the average fuel economy will be what I would consider normal for my commute. Somewhere in the 40.5-41.2 mpg range. Then the next day ( similar conditions), it will warm up much quicker and my mpgs will decrease quite a bit. Somewhere in the 36-37 range. One time in particular it warmed up really fast and I swear I saw smoke coming out the ass end ( early, dark, couldn’t see smoke color). I have read other posts where Passat drivers were experiencing acceleration lag, might these issues be related? What sensor/system might be the likely culprit? I appreciate you taking the time to read this. Bless all you diesel lovers out there.