I don't know about the older ones, but the newer ones certainly aren't immune.

My brother in law has a 56 plate E90 320d M Sport 6 speed manual, which he bought from a BMW dealer (Approved Used) a year ago. A mint, one owner, 30,000 mile example, it seemed like a good buy. In practice, it's been one of the most unreliable cars he's ever owned, and the DMF needed replacing at 34,000 miles (along with the clutch and gearbox!). A new judder has surfaced again in the last few weeks, and the dealer suspects a second DMF failure. The car has not yet done 40,000 miles. He doesn't slip/ride the clutch, or partake in aggressive launches or gear changes, and his previous DMF equipped Golf mk4 TDI did 140,000 miles with no DMF or clutch issues. It is a vehicle/manufacturing fault, not his driving style.

The dealer has told him there's a software update for 2007 on models which performs some trickery with the revs on pull away and masks the judder (bodge, anyone?) but it doesn't apply to his car. It's going in again shortly for the new gearbox to come out, and the problem be investigated for a second time.

Apart from a near complete transmission replacement at just over 30k, and the problem resurfacing again less than 10k later, it also puts its ESP and hill start warnings on intermittently, and has suffered various electrical problems. It's also left them stranded once. He's lost all faith in it, and understandably has no interest in owning it outside of warranty.

Older diesels didn't have DMFs, let alone DPFs. Maybe someone knows when BMW first introduced them, so Al can see how old his car needs to be.

DP, that sounds as if your B-I-L has had more problems than all of your own high-milege cars put together. If there's a trend here it seems to be that if buying secondhand and you want a diesel, go for one of the older, less complicated engines like the VAG PD or Ford TDDI / TDCI. Otherwise it seems to be better to go for a petrol: one big repair out of warranty knocks on the head any savings that a diesel's economy might have brought.

Edited by Avant on 10/04/2010 at 00:00