IMHO there were no major changes in the diesel engine for the model run. The later models have just as many emissions issues as the older ones. Other than the LCI update, the only major difference was the switch away from the gen 1 ccc nav after 09. It is really bad (especially the backup camera) and may people pay thousands of dollars to switch it out.

I spend a year shopping and got frustrated with the lack of options in the newer diesels. It was very easy to find a loaded 09 where most of the 2012s were base models.

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2009 35d, 2006 325i & 330i