I have just bought a 250 CDI AMG Sport on a 15 plate . The engine is very quiet . I had heard they we're noisy and was going to avoid but then I heard that after August 2012 the engine was revamped and made a lot quieter. A friend of mine that has a TVR Tuscan S was surprised that it was a diesel and was very surprised at the mpg and performance .
I think diesel sports cars are here to stay oh yes and the road tax is only £130 .
Michael.
I don't think our 250cdi is particularly noisy but I accept I haven't compared it to the driving experience of a petrol.
Last summer (top down) I was passed on the A14 by a porsche (can't remember the model). We both turned down the A12 towards Colchester in mixed traffic. I kept pace with him and the main noise in my car was his engine/exhaust rather than my diesel engine.