Edit: 1/3 Music - Bose QC Buds - Google's Assistant - Android Enthusiast Website
Solved the problem:
I'm using Samsung Music Player
I say, "Hey Google, Play Samsung Music "
And it worked
I shall have to split my answer into probably 3 posts because I will have to take more than 2,500 limit to properly deal with the topic.
1: Probably, the problem isn't what car you are driving, but the quality of the installed radio system, earbuds, earphones, headphones, and apps being used.
2: Google Assistant doesn't know what music player you want to use -unless you are inside the correct music player that you want to use, and also the music player will actually play the music and also is compatible with the Google's Assistant that are compatible with the latest voice commands.
3: If you weren't inside the correct music player - Google Assistant will probably have to guess, which place to go to, for example, to play the music requested.
4: I shall tell you how I managed to solve the problem eventually, but you should replace the things that I use with the ones that you use.
5: But I don't know if the things that you are using are good enough (have the latest software) for Google Assistant to take advantage of the voice recognition commands.
6: Make sure that you are using the latest updates with products.
7: Replace my items with the ones that you use.
8: I use the Samsung Galaxy S20 Ultra phone - You should replace it with your phone each time that I mention my phone, S20 Ultra.
9: I've got the latest Android 11 version that should be good enough to operate Google Assistant voice.
10: I've got plenty of spare storage space on my phone, because as far as possible I save data onto my relatively fast read and write SanDisk Extreme Plus, V30 128GB, MicroSDXC Card inside my S20 Ultra's Phone (Ccleaner app may help to increase storage space).
11: I transferred data from my phone using Myfile that either came with my S20 Ultra's Phone or that I installed from Google's Playstore.
12: I then moved (cut and paste) data using Myfile inside my S20 to the SanDisk Extreme Plus 128GB MicroSDXC Card.
NB! (Note well)!
NB! If necessary used Samsung's (phone's) Technicians to solve any compatible problems with; Samsung Music Player, and Myfile, to allow Google Assistant to be able to automatically find all the relevant music, and play them.
I, shall check that commands work in 2 and 3.
Divide notes in Google's Doc App into half and hope that both halves are within the limit - copy and paste into this forum.
Hopefully, these 3 posts will help people to use voice commands within their products.