Sorry. That does seem to be the case but it seems intermittent. From what I can gather, email does work on occasions with the following conditions.
1) Email must be set to preview in lock screen
2) Some have said that emails must be set to show in notification centre.
3) Some have reported that the phone must go into lock of its own accord. i.e. pressing the lock button does not work
4) An email must be received in the car whilst the phone is locked. It does not transfer old emails (read or unread) and it will not transfer emails received when the phone is unlocked.
5) Even with all these conditions met, it has been reported that it only works the first time it is set up. It stops working after you have been away from the car.
Personally, I haven't tried it, but I'll be glad if people can get it to work. I like being able to see SMS messages and I'm sure I would also find emails useful.