I can speak fairly and squarely about modern diesels from actual experience, because i put 8,000 miles on my 2006 535d. (I also own a 55-plate Honda CRV 2.2 diesel which is superb).
The BMW was fast standard and very quick indeed after remapping to 334bhp. That same remapping surprisingly improved the fuel consumption and raised the torque to a monumental 506 lbs. I saw an average of 38 mpg taken over my last 4 tankfuls. The best i saw was almost 50 mpg and the worst 27 mpg.
I have to say that the slightly noisy idle never worried me, neither did the roar when really going for it.
I realise that Palmy and Noxy don't like diesels and that's fine. But as an owner of one of the most 'petrol-engined' cars ever sold, my current M3 CSL, i have to admit my utter respect for the 535d. A brilliant car which did just about everything well and has to be up there as one of the best all-round cars on sale anywhere at any price.
Very fast, very comfortable, handled much better than i expected, well equipped, very high crash protection, capable of effortless 150 mph cruising where allowed. After delimiting it did 175 mph too.
Bear in mind that the new 2006 335d has a lighter engine, which produces more power and torque in a car weighing less.
I absolutely love the banzai CSL but i also loved the 535d.
(Sorry Oli and Andy!

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6R4. The Beast!