This article explains several methods to listen to your iPod in the car.

The easiest way to listen to an iPod, iPhone or iPad in the car is via a USB or auxiliary input, Bluetooth connection or iPod Direct Control. But if your car doesn’t have any of these connections, you’ll have to get creative.

Depending on the head unit you have, there are three options you can consider for using your iOS device: a car cassette adapter, an FM broadcaster, or an FM modulator. These are all viable options, and they essentially add a temporary auxiliary input to your sound system. The best option for your situation, however, will depend on a number of factors.

A car cassette adapter is the easiest and cheapest way to listen to an iOS device in a car without aux. This is only an option if the head unit has a cassette player, which is increasingly rare.