Aiwa is a manufacturer. Their car stereo plays CD's which music in normal and in MP3 format. About 13CD's can be burned to one CDR. I am not sure if it plays CD-RW's. But there are other manufacturers, there have been(sold out) even standard carstereo size units which have an internal harddisk. I was to early and then to late to get one. Real cool as far as I remembered it even had a LAN port. Have a look at Creative Labs "Jukebox" one version, mine holds the contents of approx 110CD's and just loops into my stock stero with an cassette adapter, if one hasn't got a propriety "line in". With Creative Labs having been pioneering in Hardware MP3 players, I am a bit surprised they have not brought out a "Standard Car stereo" sized player themselves. Maybe we all should send them emails demanding one. :) Best Regards Ralf