Four options are possible which will allow you to playback music stored on or streamed via your Android phone to a typical car audio system.
Probably the most obvious solution is to use an analogue cable connecting the headphone jack on your phone to the line-in option on your car’s audio system. There are various ways in which this can be done.
For instance, you might have a standard line-in connector mounted on the front of your car audio system, providing easy access. Alternatively you may need to work the connection around the back of the dashboard in order to hook up your phone and enjoy the tunes you have stored on it.
Older audio systems with a cassette tape player will allow you to use a cassette adapter, a small, low-cost device which connects to the headphone jack on an MP3 player or phone allowing you to play music through it and into the car audio system.
Note that when using the analogue option you have two volume control options, that of the audio system and that on your Android phone.
BluetoothMany modern car audio systems have Bluetooth as an option for playing music across a short-range wireless network. In order to take advantage of this, begin by activating Bluetooth on the car audio system, making sure that it is discoverable.
On your Android device, open Settings > Connections > Bluetooth Settings and activate the Bluetooth option. Below this, wait for the screen to update and display your car audio system, selecting it to pair.
The cool thing about Bluetooth is that it will pair automatically in future; the not-so-cool thing is the impact on battery life, resulting in you keeping your phone charged while using it.