Fraser - I know the 35d has TT - I own one remember ;) My point is that I bought the 35d over the base 30d so that I would have a bit more in-gear response ..but just not feeling that until the second turbo wakes up and kicks .. my point is that its not as progressive as a TT until should be ..might just be a characteristic of diesel engine ?! I understand its heavy - but that has little to do with the timing it takes for the turbo's to spool ... has the 40d moved to single turbo twin scroll? perhaps that why BMW have moved that way (or they are just trying to save $$) ...

I've driven the 35d back to back against the 30d and the twin-turbo 35d is better off the bottom end, slightly better in the mid-range and, most noticeably better in the top end. I think that you are a hard marker.

The 40d still has two separate turbos (unlike the new 35i which has moved from twin (parallel) turbos to s single twin-scroll unit). The difference between the 35d and the 40d is that with the 35d both (in sequence) turbos are fixed geometry whereas with the 40d the small turbo is variable and the bigger turbo is fixed.

Yes, the lack of response just off idle, or lack of progressive response, is a diesel characteristic, since they depend so much on the turbo system (compared to a petrol engine of the same displacement) The tri-turbo diesel coming soon is an attempt to further improve the throttle response, by providing the required boost and throttle response throughout the rev range. If you just put bigger turbos on to make the required boost you get lag, so it is a constant trade off for the designers.

I agree, but I also think that it's also a non-issue especially since the auto 'box does a good job of masking the off-idle pick up even with the single turbo 30d, let alone the twin-turbo 35d.