Though it's marketed as an e-reader, several members of the Kindle family of devices also offer a full spectrum of entertainment features. The Kindle Keyboard is equipped with audio capabilities for playing audiobooks and other MP3 files. All of the Kindle Fire models play not just audio files, but fully support high resolution gaming and video streaming like Amazon Instant Prime Video and Netflix as well. An auxiliary audio cable can be used to bridge a connection between the device's headphone port and your car stereo so you can listen to your Kindle audiobooks in the car.
Plug one end of the auxilliary cable into the headphone jack on your Kindle.
Plug the other end into the AUX port in your car.
Configure your car stereo to play from the auxilliary input.
Launch your audiobook file.
You may have to fully raise the volume on your Kindle device for a good quality sound on your car stereo.