Finally someone brought a dedicated MP3 player for cars. I know there has been many minor projects going on, based on Linux, etc. but this is finally a "mainstream" product from a big company. Player is made by Aiwa and you can check its very minimal specs from this link.
Player plays audio CDs and CD-R(W)s with MP3 files. Specific specs about the MP3 playback are not available yet, but hopefully soon.