In BT4 because of the new bluetooth stack (bluez 4 instead of bluez 3.x) the tool carwhisperer doesn't work anymore.

It is possible to start it, it will connect to the headset (if default PIN was set correctly), but it doesn't record anything (it fills up the output file with zeros).

Maybe I screwed up something with the settings (however this is highly unlikely), but you know too that bluez 4 has no documentation at all, so figuring out how to change settings is really difficult.
I would highly recommend (if the newer kernel still makes this possible) to return to bluez 3.x.

Thank you,
DOMy