Unless you live in rural Wyoming, the FM transmitter just isn't going to do the job. I've read a lot about the
http://icelink.densionusa.com/ system and many of my friends have experienced great success with it.
The system is $219 and requires connection from the back end of the car's stereo. Once installed, the IceLink acts as if it is the CD player and the driver can change songs etc. from the car's stereo controls.