Right Lane
Active member
I've got about 4500 miles on my 2013 Golf TDI with DSG. I understand that there will be cold-induced parasitic losses to my mpg but I'm experiencing greater losses than expected. I commute the same route daily - about 70-miles round trip through stop-and-go to 65 mph. I use Shell fuel only from one of two stations who discount steeply (ensuring supply turnover). I have the factory Continentals that are set cold at an accurate 40 psi at an ambient outside temperature of 28F. Accessory load is the same from day to day. My measured mpg calculated at fill-up has varied from just over 36 mpg to just over 42 mpg. Now the problem: The MFI average seems to be pretty accurate and I will check it at the same point into my daily commute (this is during the morning portion of my commute and 90% of this is with the cruise control set). When the local temperature spiked to 60F last week, the MFI indicated 48.0 mpg at my check point; however, at 8 or 10F I'm looking at less the 30 mpg at the same check point. I realize that the atmosphere is more difficult to punch through at colder temps but for the life of me, I'm at a loss to explain this much of a discrepancy. Others must be going through this too and I'm wondering if something is going on in the combustion process that I'm missing?