So both my wife' sand my iPhones are having consistent issues with bluetooth. we're on the .43 variant of 6.0. We had it iOS 8.0, 8.0.2, and now 8.1.
What I noticed is that when the phone draws data via LTE, the Bluetooth connection seems to drop. I first noticed it streaming music via Spotify. If I have the playlist downloaded on my phone,it wouldn't have any issues. But when I am truly streaming music via the LTE connection on my phone, it would disconnect. But here's what I do to recreate it fairly consistently:
Connect the iPhone and stream music from a music app, like Spotify. Then, open the "Speedtest" app on the phone and run a test. Somewhere during the test, the bluetooth will disconnect, momentarily disappear, then re-appear. But I have to manually select it to start the music back up.
Can't say if it's the iphones, iOS or the Tesla. But as I said, it happens on both phones.