1. I saw an FM player that would work with an iPhone G4 in Staples on sale in the clearance box for $20 off to about $65. It plugs into the lighter for power.
2. However, if you have a cassette player in your car, for about $15 you can get a casette-shaped converter with a cord that plugs into your iPhone in the earphone plug, and then plays through your radio. This requires no power.
Oops, that “FM player” is actually an FM transmitter.