On my iPod when I am using it with my bluetooth headphones everything is fine until I get into a vehicle that I have set-up bluetooth so I can hear it through the radio. 

Is there a way to keep the bluetooth connected to the headphones without deleting the vehicle(s) in question.  It even happens if someone else is driving the vehicle by me and then my iPod will go and connect to the other bluetooth source and quit going through the headphones.