Siri on Volkswagen RCD 310 using Bluetooth How can I get the Volkswagen RCD 310 radio/CD player to work with Siri? 

When iPhone is connected to the car using Bluetooth telephone connection and I press and hold its home button, Siri starts, but nothing happens in the car: It does not stop playing music, the alert sound does not play over the car's speakers, and I cannot hear Siri answer my request even though the conversation is displayed on the phone's screen.

Version indication: iPhone 5S with iOS 8.2

[EDIT] when using the phone as Bluetooth media player, when I press the home button to start Siri, I can hear the tone, but I cannot hear the answer to my requests.
Found a reliable yet cumbersome workaround to have Siri play over the RCD 310 stereo using Bluetooth... 


Using your car's steering wheel control, disconnect the Bluetooth link to your phone.
Open Siri by holding your iPhone's home button. 
Re-activate the Bluetooth connection from your car to your phone.


Voilà, after a few seconds you can have a dialog with Siri in your car... at least until you leave the Siri screen.