Sami Pietikainen has written an article detailing the build of his Bluetooth DAC using Raspberry Pi Zero W:
My car comes with a built-in Bluetooth hands-free but unfortunately it does not support audio streaming. Luckily there is an AUX input available which uses a regular 3,5 mm jack. Perfect opportunity for a DIY project. I built the Bluetooth DAC using Raspberry Pi Zero W and a DAC hat. This post depicts the details of this project.
See the full post on Page Fault Blog.
