I have now got SMS messages coming through into iDrive from my iPhone 4 with IOS6 on my 2011 335i.
You need to get the latest Bluetooth update from www.bmw.com/bluetooth
, enter your VIN and put the firmware bin file on a USB stick and upload the file into your iDrive via the BMW Firmware Update section.
SMS messages will only work as the email part of the new IOS 6 pushing emails thru to the iDrive has a bug.
Delete the existing iPhone pairing and re-do.
Under Settings, Bluetooth in your iPhone, go to the devices connected where it shows your BMW has paired, open that and turn on "Show Notifications".
Then under Settings in your iPhone go to "Notications" then under each heading "Phone" "Messages" "Mail" make sure you have the following turned on:
Notification Centre ON
Alert Style Alerts
Badge App Icon ON
Show Preview ON
View in Locked Screen ON
In iDrive you also need to tick "Office" in the bluetooth options. Then you get 3 options under "Office" in the main iDrive menu (Contacts, Office Today and Messages) where you can filter messages.
The TXT messages will only transfer to your idrive when your iPhone goes to sleep and has a blank screen (Locked) hence the View in Locked Screen, without this setting and your iphone has turned itself to Locked will the message be transferred, if you open the iPhone to view the messages they won't transfer to the iDrive, iPhone must turn itself to lock so set your iPhone to lock after 1 Minute in settings.
Emails are the same but that has a bug at the moment. Hopefully this should be fixed by Apple soon as it was working in their beta IOS6.
I'm pretty sure you need cars fitted with the Combox interface, so that means only recent models.