Have you ensured that both Bluetooth devices are set to be discoverable? If not, then they won't be able to "see" each other in order to pair up.
If I recall correctly, on your phone the discoverable mode only lasts for about 2 minutes, so if there's a delay in programming your car to search for the phone then it's possible for the phone to revert back to hidden mode before pairing is complete.
If these suggestions do not solve your problem then please add a comment to state the EXACT year and version of Passat which you have and which country it was first sold new in.
Answers & Comments
Have you ensured that both Bluetooth devices are set to be discoverable? If not, then they won't be able to "see" each other in order to pair up.
If I recall correctly, on your phone the discoverable mode only lasts for about 2 minutes, so if there's a delay in programming your car to search for the phone then it's possible for the phone to revert back to hidden mode before pairing is complete.
If these suggestions do not solve your problem then please add a comment to state the EXACT year and version of Passat which you have and which country it was first sold new in.