I was just browsing through the BMW parts catalog and I noticed that a huge proportion of e90 electronic and audio components are listed as up to 03/07 or from 03/07. A significant but much lesser proportion are also listed as up to 09/07 or from 09/07, or from 03/07 to 09/07.
Also the replacement main wiring harness is listed as from 03/07.
It seems to me that the reason that BMW imply that 6FL is not possible to retrofit is that so many components of a pre-03/07 car would need to be changed that it is not viable. And maybe they have a lot of MOST iPod kits left or committed to purchase.
I am still optimistic about upgrading post 03/07 cars.
And indeed I just noticed that there is a part number for a USB/Audio Interface Retrofit Kit, 65 41 0 443 678 which seems to cover all options of radio/iDrive/Voice/Nav, etc., built from 03/07. And better still it says that installation instructions are not included but are available (as is normal) via the After-Sales Portal. Fitting time is quoted as from 2 - 2.25 hours.
Does anyone know someone in a BMW dealer that can download the fitting instructions?