The basic engine structure (block, crank) is common to the European BMW diesel engine, and so is proven and reliable. It is aluminum, so likely doesn't have the same life expectancy as traditional (heavier built) diesels, but it will probably last as long as the gasoline engine, eg longer than the transmission. The urea injection system (emissions control) is new to North America and has had some reported problems with early production vehicles, but they are minor and generally fall into the nuisance category, likely to be ironed out in the second year of production if not already.

You will experience more throttle lag with the diesel just off idle, compared to the gasoline engine. The BMW drive by wire throttle issues may indeed make it worse, but regardless the diesel will always have a response lag due to the turbos needing to spool up. This engine does not have the same turbo arrangment as the 35i with the dual turbos, which result in far less lag. The 35i uses two equal turbos in parallel, the 35d uses two unequal turbos in a staged arrangement. There is great torque from the 35d engine, just not until you get it on the boil, ie 1800 rpm.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue