I'm actually quite annoyed by how utterly crap the DS4's iPod support is. It is simply not worthy of being in any car and every time I've tried to use it I've got angry and frustrated with how poor it is.
All I want to do is have my iPod classic plugged in and left in the car and able to easily play randomly from all the available songs (nearly 6,000) when I switch to it. When I plug the iPod in it just starts the first song alpabetically from the first artist. There's no simple option I can find to start random play. I have to go through some menus to find an option for Random (there is also a Radom All option that is always greyed out) and then start by selecting a track after getting to the song list (another example of unintuitive menu layouts).
It then displays a number out of 999 as it apparently can't cope with more tracks than that. I've no idea what the number before that refers to (i.e. 361/999) as I can't determine what order it has apparently put the tracks into (perhaps they are shuffled, but is it selecting from all available songs).
I've also found that if I skip to the next track from the one currently playing, it sometimes changes to only playing songs from the album that the next track belongs to. Interestingly, the times it has done that it has always gone to the same album (which happens to be the first album of the second artist when listed alpabetically).
Also, when using my iPod classic, it will just stop playing after a while (less than 30 mins) and claims the iPod is not connected. This doesn't seem to happen with my iPod Touch.
I've actually spent the last two weeks on holiday in the USA with a new Nissan Pathfinder (the one currently only on sale in North America) as a rental. The iPod connectivity system on there was exactly as it should be. It recongnises the iPod quickly and doesn't spend long "loading data". You then get a menu giving access to artists, albums, genres, podcasts etc. You also have a menu option for Shuffle All Songs which starts a random play from everything on the device. the screen displays song/album/artist info and displays the correct number of songs on the device (no stupid 999 limitiation). If Nissan can get it right, how come Citroen aren't capable of the same thing?
To be honest, it's spoiling my ownership experience of the DS4 as I always like to listen to to music while I'm driving. I end up just switching to a DAB station out of frustration. Along with the bluetooth microphone problems, Citroen need to seriously look at the quality of some of the features of a supposedly 'premium' car. It really can't be that hard to get something like iPod/USB connectivity right and easy to use given the amounts of money spent on developing cars across Citroen and Peugeot.