all the FM transmitters I've tried were terrible. I've followed all the directions and most of the time, depending if the transmitter is in a good mood or not, it will always have a fuzzy feedback. I suggest sticking with the mp3 adaptor (the one with the tape casette on the other end audio jack). Most new cars today would come with an audio input so youd be able to stick an audio jack from your ipod into your car.
Then again, these also get so-so reviews, but they've always worked like they're suppose to for me.