My experience after 8 months daily driver on a 62 mile commute:
I use magnetic mounts from WixGear as found on Amazon to hold the phone to dash or vents in my different vehicles. They work well, but you may have to be clever to find what will work in some vehicles.
For me, BT works for media player in some cars, mostly older ones, but not for phone at all.
Wired worked fine for both, but it stopped recognizing my wired mic about six months ago. Using the built-in mic for phone calls works, but the audio quality for the other party ranges from OK (low speed, no A/C) to almost unusable (high speed, max A/C). If this isn’t fixed in the next PureOS version, I will try to mitigate things with Noise Torch.