Got this email from Nokia today. I have also emailed Seat on the same matter, but expect either nothing or as wooly a response as this back from them:
Dear Rob,
Thank you for emailing Nokia Care.
In response to your enquiry, we have tested our phones with accessories manufactured by Nokia. As such, I am unable to confirm the compatibility and operability between Nokia products and third party manufactured products.
I would recommend that you explore the compatible car kits for Nokia N95 and E50.
The compatible car kits for Nokia N95 are as listed below:
1) Nokia Bluetooth Display Car Kit CK-15W.
2) Nokia Multimedia Car Kit CK-20W (you may use the supported handsfree mode).
3) Nokia Advanced Car Kit CK-7W (connection via bluetooth)
On the other hand, Nokia E50 is compatible with the following car kits:
1) Nokia Wireless Car Kit CK-1W.
2) Nokia Multimedia Car Kit CK-20W (you may use the supported handsfree and navigation modes).
3) Nokia Advanced Car Kit CK-7W (connection via bluetooth).
With regard to a software, please note that there aren't any available to enable the compatibility between Nokia products and third party manufactured products.
However, I will certainly forward your feedback to the relevant department for future consideration.
Kind regards,
Bhanu
Nokia Care
So basically, don't hold your breath for a firmware update for the Nokia Symbian phones to operate with these things, they're only bothered if their own kits work. For the first time ever I am now considering a phone make other than Nokia.
Rob