That's interesting. I sometimes wonder at the differences between individual examples of the same engine. I drove two Panda multijets (one on an extended test drive) before buying one and was disappointed to find the one I bought to be far noisier from day one. As for our Sedici, it is obviously noisier from inside than the A4, but that's just down to the extra structural isolation and soundproofing that comes in a £23K car. Listen to them from outside bonnet up and the Audi is the noisier of the two. On the move at 50mph, there's remarkably little in it.... We also lived with a (new) Bravo for a few weeks. This had the 1.9 Fiat mjet and was swapped directly for the Sedici. The engine noise levels from outside were very similar, but the Bravo was somewhat more refined from the inside (probably again a feature of better soundproofing & vehicle design).
If you want to do an aural urban pose, it really it has to be petrol. As Clarkson said of the diesel Brera, diesels exist for people who "want a moustache on their mona lisa". And for people with high torque needs as in butch 4x4s. And for tightwads. Which has to be most of us these days.. sigh!