For any ipod user, do yourself a favor and connect via dock connector not the headphone connector. On the X3 and most newer cars w/ USB port, definately go USB. If you only have an Aux-In, get a cable like this:
http://www.ramelectronics.net/ipod-m...rodIFEPDM.html
Not endorsing specific cable, just a type.
The ipod audio connector is amplified w/ volume control, and never sounds great going to a line-in aux port on a car. The ipod dock connector audio out is a Line-Out without amplification or audio control - and when you go from the dock connector to your aux-in it sounds better. as I said, on your X3 or any vehicle equipped with a USB connector, just go with that - its well integrated. but if you are ever in a car that only has Aux-in and u need ipod sound consider this method.
Thanks for the heads up that plugging in to the Aux-In on the X3 will disable audio from USB and BT streaming. I haven't used my aux-in because i use the USB connection
as for streaming - I have a Droid 2. It never worked at first - phone would look like its playing, but no audio- about a month ago I did a full factory reset on the droid2 to deal w/ a variety of issues, since then audio streaming in my X3 works, also messages now come in to connectedoffice - or whatever its called (don't care so much about that feature)
personally i'm glad to have both USB and BT streaming working - on my old E91 the aux-in port was inside the center console and faced up - i could never find a good 90degree bend audio jack and so when i closed the center console it would apply pressure on the connector - i had to have the connector fixed twice by the dealership on my E91. The F25 X3 is much better in so many ways.