I'm having a more nuanced problem with mine - Upgraded from iPhone 6 to 8 and now, bluetooth in my 2015 VW Golf cuts out. Similar to a CD skip, intermittently the song will stop playing and "skip." I then also have issues 25% of the time when I turn the car on it will say bluetooth is connected and even show that it is playing but there is no audio. Only way to fix it is to completely turn off and restart bluetooth on the phone and car and this doesn't always work. Issue is present with Apple Music, Spotify, and Apple Podcasts.
This weekend, I test drove a 2017 BWM 330xi and it had the same exact issue.
This problem is NOT present with my Beats Solo3 bluetooth headphones, only with car bluetooth.
This is the exact problem I have.
Could you try erasing all network settings and seeing if that works for you? It didn’t for me.