While rushing home yesterday, for a family emergency, I was driving my Expedition while my wife was following closely behind in the Prius. We were talking on our respective cell phones (mine BT enabled and, obviously, paired with the Prius), she with a regular phone. during our conversation she, apparently, wandered just within connection range of my BT phone with the Prius. She described briefly overhearing her own voice through the speaker of the Prius (it was broadcasting my phone), but couldn't hear anything I said (Prius was trying to listen via the microphone). The connection was, obviously, pretty tenuous and fairly quickly broke off completely. Just an interesting occurance. I really don't think the vehicles were that close--she wasn't tail-gaiting, but probably were within 50 feet or so.
that is bizarre but possible. signal quality degrades over distance and recommended distance for BT is 9 meters or about 30 feet. but the signal is available at greater distances but is normally too weak to hear with any amount of reliability.