You and me differ greatly in terms of what one "should" buy.
I would never, and will never - get into the 335d and think "I should have kept my 2 litre diesel".
It's got the minimum power I would now accept going forward from any daily drive I will run.
If MPG is all that matters to you, the 330d will not dissappoint. It's a great engine, even better with a remap - STREETS ahead of the 320d, but still returns over 50 on a casual motorway jaunt.
Previously: 2003 Peugeot 206 1.6 8v | 2006 E90 320d M-Sport, 19" BBS CH, Full Ice-cold JL audio install, August 2010 Total BMW 6 page feature car. | 2003 Nissan 350Z GT Coupe 286BHP
Now:2010 E92 LCI 335d M-Sport