After purchasing the car I naturally did some serious repairing to fix every problem found in the pre-purchase inspection. Parts (OEM, but not from the dealer) cost some 500€, did most work myself and had a mechanic buddy of mine work on the engine.
The initial parts list included engine hydraulic valve adjusters, the rubber parts for the top of front shocks, a couple of joints for the front suspension and since the rear brakes weren't working too good I purchased EVERYTHING possible that was replaceable for rear brakes and handbrake system, except for the calibers for which I just got an overhaul kit.
Naturally I had the oil changed (premium Mobil 1) along with the oil filter, both diesel filters and air filter prior to starting to use the car. Doesn't quite count as a fault, though :-)
Actual problems so far:
The transmission started slipping on 2nd-3rd change. Fixed in a few minutes by adjusting the transmission pressure from the pressure switch on the side of the transmission. Thank you MB engineers! Wish Bimmers had this kind of switches too, would have saved me lots of money on my former 750i.. Cost: 0€
The 17-year old power steering hose busted as I started the car in extreme -33C. Cost a few bucks plus about a litre of ATF220.
There was an unfortunate oil leak right after the oil change. A sort of valve, the kind you see on the coolant system to protect the block from breaking if the coolant freezes up, just on the oil system this time, had been slightly open, blocked by remains of inferior motor oil and started leaking after some driving with the highly cleansing premium oil. My buddy changed it for free, but I lost 50€ worth oil which had just a few hundred km on it :- (