The 325Ds have a single turbo and the 330/335Ds have twin turbos. I have a 525D (same 3 litre engine) and there is nothing like a smooth 6 cylinder TDI.
Alex
Incorrect....the 330d is a single turbo, the 335d is a twin turbo
I currently run a 335d E92 coupe, running a DTUK CRD-T tuning box and make 340bhp, 510 lbs/ft torque, my car returns an average of 36/38 to the tank with mixed driving and spirited driving.
On a steady long run I can get 50 ish mpg .... Constant 70/80 on a motorway.
I'm on my second 335d coupe now, I love it, best of everything IMO....looks, power/performance, economy and nt expensive to run either.
The only negative side is the tyres, good quality branded tyres aren't cheap, but all in all, they're a great car !!
The 330d is equally as good, just not a quick and I prefer the power delivery of the twin turbo over the single turbo found on the 330d
Oh, and the auto box with sport option (paddles) would be better if your planning on a power increase, otherwise you'll be forever changing gear !!