A long time ago, when Bluetooth was even less reliable that it is nowadays, some people had luck with pairing devices under less than ideal circumstances.
Example:
Pair a phone with the headset in your ear and the phone in your hand and you had problems with dropouts.
Pair the same two devices again, except this time stick the headset in a metal filing cabinet and do it from across the room. Now when used as intended (headset in ear, handset in pocket) the dropouts are gone.
It's almost as if the initial pairing sets the transmit power levels and they stay that way.
In my case, the distance I can have is stunning. The Avic/phone combo is cranky in every other respect but distance. I have the Viper SmartStart app on my phone, so I fire the truck up about 3 minutes before hopping in to warm it up. I have Tasker set up to set my phone's media volume to max when it pairs with the Avic and does a little beep notification when the task kicks off. I get that beep a good 30-50 feet from my truck. Impressive. It's cool but I'd rather have it not require a phone reboot after a call to start working again.