Originally Posted by sfax
I think that's only true if you have the tech package. You still need a Y cable if you don't This has been covered at length here
I read through that thread, and it didn't really seem to converge on a solid conclusion. Let me tell you what I know.
Some BMWs past March 2010 production and all BMWs past sept/oct 2010 production can be 6VC "combox" equipped. Among other things, that allows recent model iPods and iPhones pass audio over USB. Older iPods do indeed still require a y-cable, but newer devices do not.
As long as the X3 has 6VC, it can use the Apple cable to transfer music on iPhones and an iPods. As far as I know, all X3 models should have this option, but it may be that it's only X3s with certain other options. It doesn't necessarily have to be the tech package. There are some individual options (ex, BMW Assist including Mobile Office and Bluetooth audio functionality) that use combox.
My 2011 Z4, built in November 2010, has 6VC standard and works with the Apple cable on my iPhone 3GS and 4. The car does not have i-drive or nav, only the "iPod/USB" option (which happens to be standard on the X3).
Bottom line, look for 6VC on your spec sheet. Cars with that code no longer need the Y-cable for iPhones and recent iPods.