There's a couple of things here.

Shuffle - When the head unit enables shuffle (usually it is either on or off so we can't get too complex), the unit will shuffle all the tracks in the current selection. i.e. if you select an album, it will play all the tracks in the album shuffled. If you select an artist it will shuffle all tracks from all albums by that artist, and the same for "type".

Recent albums - one of the buttons on the head unit is the "play last ripped album" button. Repeat presses of this steps back through the albums in reverse-ripped order.

Tracks you don't like - although we rip entire CDs for ease, you can delete the current track or current album. This means you can pare albums down to just the tracks you like. Unfortunately, that means they are not available at all. Still keeping the album (or part album) as the smallest unit. If we get into track management, complexity becomes too much to do with this interface.

"playlists" - the "type" id is user-defined (although we may have some in there to start with). The user can delete them or add new ones, so you can have the "Daughter in car" type as well as "hardcore thrash" type (if that does it for you ). You can move or copy whole albums (or what is left of them) between playlists, so they can be used as a kind of cross between playlists and genres. Moving/copying albums between "types" would be done only at the remote unit (probably when you first add the CD), to avoid complicating the head unit interface. This would hopefully do almost what you want, although you still couldn't select only a few tracks from any particular album without deleting the rest.

For those users who start fresh with no current mass music storage, this would be fairly easy to do. As each CD goes in, they can put it in whatever categories they see fit. It is a bit more laborious if they want to dump 10Gb of music in to start with though!

There are a couple of advanced possibilities that could be set in the remote unit. Onet would be to allow the user to select what random meant when the head unit selected it. It could be true random, or least played or etc...

Any alternatives always considered

Thanks

Nick