[Sshire]

No nav. Standard audio. iPhone 4s.
I use the TomTom iPhone app for my navi. If I'm not alone in the car, i might want to have a conversation with passengers. Since there isn't a function to stop playing music ( at least I haven't found one) I press the iDrive button or the volume knob to pause the music. Cleverly, this also stops audio instructions from TomTom.
My next thought was to create a blank MP3 track and set it to repeat endlessly so that I'd still have navi audio directions. No, no no. No repeat feature.
Maybe a playlist with my blank track 100 times.
This is crazy. How hard is it to have a "stop playing music" option.