Yeah on that BMW note though, it's interesting how, from a personal perspective at least, polarised my opinions are regarding Munich's derve-flavoured offerings...

4 cylinder diesels - limited appeal, unrefined, noisy, narrow torqueband etc. I'm referring to the new 320d I drove on the weekend.
6 cylinder diesels - smooth, characterful, wider torqueband, tuneful, ballistic. I'm referring to just the E46 330d a friend owns. I can honestly say that the six cylinder diesel is just about one of the most appealing powerplants I've ever had the privilege of driving.

So, it depends on the type of diesel engine.