Perhaps you already know this, but if you don't, here's a cheap and easy way of running the sound from your iPod or other MP3 player through your car radio.
If you have a cassette player in your radio, as I do in a 1997 Camry, and ever had a personal CD player that you plugged into a phony cassette and shoved into the cassette player to play the CD through the car radio, you can do the same with the iPod .....just resurrect your old phony cassette, with the wire coming from it, and plug the wire into the iPod, and turn on your radio, and you're good to go! I was thinking about this and was bemoaning the fact that the radios in my Toyotas were of an age when they didn't include an input socket on the face of the radio, when I realized that the miniplug of the phony cassette matches the earphone socket on the iPod. Voila!