If you are synced with Bluetooth and you hold the home button for Siri it works through the car audio.
You do have to handle the phone, however.
Dave Flogaus CCA #123862
Instructor, BMW Club Racer & Nürburgring Specialist
95 E34 M5 3.8 Daytona Violet
13 E70 X5d Workhorse
14 F31 M Sport Touring