Well, as it's well known, people can use the radio and let their friends listen to the music, but that's as long as everyone is in the car. There are some things that in my opinion, should be improved.
First, the music stops when the driver (the one that plays the music) gets out of it. In my opinion, that shouldn't happen, the same song must keep repeating, till the the driver changes it, he should also be able to keep reentering, though once people enter, they will be able to hear it straight away. I'm sure that this will be liked by everyone, because it's quiet annoying to have to reset the song every time you get back in.
Now, the second one that seems a bit more difficult to happen. Well, it's something familiar with the admins' speakers, but that's a bit more different. For example, I'm driving my Picador, currently, just me and 1 more person can hear he ongoing music. Is it possible to make it like, familiar to the admins' speakers, yet with like 1/2 of the power of the speaker itself. Now, obviously, this might bring a lot of chaos, everyone will play their stuff, but first - if decided, that ability could be paid, second, if the driver gets out of the car, thus goes to a SR for example, the sound coming from the vehicle will go down with the time passing by, till the moment that he enters back in and gets the volume back to maximum. This way, there won't be weirdass musics coming from everywhere in JBs, SRs or wherever.