We have a 04 Nissan Armada that has the Line In input on the dash near the radio and have had no problems with the Belkin car charger with the Line Out feature. So, before we went to Munich to do our ED I picked up another one. And it sounded like crap in the BMW, when you had it plugged in to the armrest socket. Getting alot of feedback so we ended up just using the head phone jack. Passable but I know it can do better.
While looking around the internet after we got back to see what I wanted to do I stumbled onto this:
No innate charging capabilities but you can buy a standard USB car charger to plug into it from what I can see. Picking up the car tomorrow finally so I'll let you know how it works out.