[TimV]

The AC has its own 2 electrical fans. The fan i aim speaking of is the fan behind the radiator that sucks air trough it.

I did no mods to get hotter air, you want colder air, the colder the better in a diesel.

I was planning to change the oil in the gearbox and differential, but didnt do that already.

This is an 2 (rear) wheel drive version. So no spinning parts to the front wheels.

Roof racks and antenna are still on, cause i like the looks of it

The only big mods i have planned to do are: belly pan (and remove it for yearly car inspection), side skirts, rear tire spats and active grill shutters (for the lower grill opening).

i aim closing this year off at 5,9l/100km (the car is rated at 8,1l/100km combined)

The reasen why diesels use more fuel in winter is following:
-lower energy winterdiesel
-colder air means longer heat up time of all components (engine, transmission, differential, tires, ...) so longer more losses
-thicker air means higher drag and CD.