So far I've changed the Air Filter (old one was 6 months old), the fuel filter, the Oil filter (6 litres of Mobil 1 fully synthetic 10W 30 plus one litre of Slick 50).
I tipped injector cleaner into 1/2 tank of fuel and me the missus and the rugrat just got back after a 350 km drive thru NL/ Be/ And Germany.
We ran the tank almost empty then filled up with 60 litres of fuel. Apart from a marginal performance increase the black smoke is still there.
A disturbing thing I have noticed is oil spits out of the dipstick hole on tickover (with the dipstick removed) this indicates an over pressuized sump (loss of compression). Strangest thing is this car will start in -18C first crank and cruise the autobahn at 160km/hr (100 MPH).
The thick Black smoke occurs only when pulling away or on kick down, the rest of the time it's not there.