I spent part of yesterday fussing with my new phone, trying to get it to behave nicely with the Bluetooth on my '12 Five Touring. Prior to having Bluetooth in the car, I wouldn't have known or cared whether it worked right, but I've kind of gotten used to having it!
My old phone, which I've now had for probably five years, doesn't provide fancy features like track and album information displaying on the dash readout, but has always behaved very predictably via the Mazda5's Bluetooth, right down to keeping the same spot on a track when I got back in the car after a stop - especially useful when listening to mp3 audiobooks with 60 minute tracks. My new phone has lots of nifty features, but it's all wonky in its Bluetooth music player behavior, very often starting a paused track playing over the phone's speaker as soon as I turn on the car, even with the radio off! It's even once in two days of ownership failed to connect a phone call to the car's speakers, which is crazy distracting when I'm driving.
The phone manufacturer suggested checking the devices' Bluetooth profiles for compatibility ... I think I've managed to obtain the profile information by connecting my Bluetooth-enabled laptop to each device (including the car!), but now I'm not sure what to do with the information other than show it to the store tech rep who sold me the phone and ask if he knows anything.