Can i use my IPhone as a Bluetooth transmitter?

I Recently got a pair of Bluetooth headphones, and they work great just one problem, every time i want to switch to a different device i need to re-pair the headphones. This isn't to much of a problem but i suspect there's a more effective way to go about this, Can i "import" audio into my iphone from say the radio via a 3mm audio jack and transmit that audio to my headphones via bluetooth( That way i could run an audio cable from my car stereo into my iPhone) and not have to spend time re-pairing. This would be the best idea i could come up with because in this scenario i wouldn't ever need to re-pair. In scenario two i spend a load of money buying a TV RCA Splitter and clicking a button for what device i want and then, out putting it to RCA-Audio and importing it into some sort of bluetooth transmitter. Any ideas?

Don't know.