The original poster obviously has experience of VW Golf diesels and the fact that the Mk7 is new and used in winter doesn't fully explain the extent of the poor consumption.

Triskaidekaphobia then?

Fear of the number 13? Eh?

Back to the OP.

I can sympathise. And being a owner of a few VAG cars over the years (SEAT/VW/SKODA) and an active member of other forums, I think I recognise a trend.

My observations and opinion:

Newer engines seem to be built much tighter when new and though some seem to loosen up fairly quickly, many others take much longer or never do loosen up. My pet theory is it may be partly due to todays factory fill full synthetic oil combined with too gentle run-in regime, that effectively means the run-in wear/loosening up never occurs.

Recent press also seems to support long held beliefs that the EU directives on fuel consumption lead to highly creative manipulation of CO2 figures by manufacturers desperate to reduce their average CO2 targets, which if they miss the EU limits lead to massive financial penalties.

My advice to the OP is: don't mollycoddle the engine - rag it every now and then and get that engine loosened up in the first 10k, otherwise it may never loosen up.