A device that enables an iPod to work through an automobile's audio system. iPod car adapters are designed for iPods only; however, generic MP3 car adapters work with iPods as well. Any car adapter that uses the headset jack (analog out) for connection works with any digital music player or portable sound source (see MP3 car adapter).

iPod-only adapters connect via the digital dock connector, which is a bi-directional port that can be used to not only deliver the music to an external system, but can be used to control the unit as well (see iPod dock).

Direct Connection Option
The best type of iPod adapter makes the iPod part of the car's entertainment system and plugs directly into the iPod's dock connector port. The buttons on the dashboard and steering wheel are used to control the iPod, and music track information is displayed on the car's built-in screen.

Roundabout Connections
FM transmitters and cassette adapters provide two easy ways to attach an iPod by pretending to be a radio station and a tape cassette. The FM transmitter, also called an "FM modulator," retransmits the audio as an FM radio signal that is picked up by the car's antenna, while the cassette adapter uses a modified tape cassette.