Make sure you're using the 2A USB Cig output lighter thingy. 1A not enough for most large phones these days. My 2A charger worked great with my old Sony Z Ultra with Waze and music on.Hmm waze normally already sucks a lot of power on my android, charging from the ciggy also does not seem enough for my phone if using waze as it will still drop just not as fast. So if use this setup then should be even worse.
I never use spotify also, don't know if they have my type of music/artists, most likely not.
Spotify has quite a large variety actually. You'd be surprised. I found Chinese music in here which is normally impossible for me to find since I don't read or write Chinese.
You're not much of a car audiophile then I rarely listen to radio these days except BFM interviews. BFM music isn't that great and I hate ads. USB music I only listen to FLAC.Still old school on radio and sometimes new school will be thumb drive.....hhahahhahah