Originally Posted by hjvelez
Mine worked fine, kept the charging functionality. I eventually stopped using the extension cable in the car because it was thicker than a normal iphone/ipod cable and didn't want to damage it with the center console lid or end up deforming the console rubber. Its up to you, and if you get a thinner cable it'll work fine. I just threw my old ipod in the center console with the Y cable and ended up using the extension cable to charge my phone at home, iphone cables are really short too. It charges fine also.
I believe that the functionality varies across model year. I've read that the 2011 and newer cars don't even need the BMW Y cable - you are supposed to be able to use the Apple white cable in the new cars.
Apple changed the charging functionality between 2007 and now so YMMV