Thanks, that’s what I was looking for. We have separate accounts although due to constant “issues” with using my Spotify account ( nothing to do with multiple drivers) in the car as it kept searching for music when I drove the car after streaming Spotify at home, I made a separate Spotify account for the car and loaded my music in there.
For some reason when my wife enters her Spotify account to her profile and saves it, it moves to mine as well. Probably doing something wrong in saving it. Will try again.
I had considered doing exactly what you said you did (making a separate spotify account for the car) and then having us both share our playlists to that account. I just never got around to it, because frankly we dont drive each others car that often. I have had my model 3 since 2018 and still love it, I only "like" her model Y (I am not a fan of the handling, and its bigger than I like to drive on a regular basis).
Conversely, my wife loves her new model Y and only "likes" driving my model 3 (she says its too small, she cant see past other cars, and she feels vulnerable in it). Kinda standard for people who prefer either sedans or SUVs actually, lol. I drive her car to "cruise" or do runs to the store when I want the carrying capacity, etc... and she only drives the model 3 when I using the model Y for some reason or other and she wants to go somewhere.
Anyway, while we both use them both, its not super often, so I never got around to making that extra spotify account, then, they came out with this feature which solves one of the problems I was trying to solve with having a separate account.
The other one (the fact that the playlists dont seem to update at any frequency I can determine, and only seems to load a subset of songs in the playlist) I have just basically resigned myself to "thats how it is" and stopped looking into, or trying to fix.