I believe they are talking about the snap in dock. if you use a cable, you wont need an adapter at all. just use the USB cable provided with the iphone 5 and connect it to the USB jack in the car.
Originally Posted by Stealth.Pilot
Its pretty clear. You can buy the dock adapter cable to use the iPhone 5 with iPhone 4 dock in the BMW.
2012 BMW 528i, Premium, Sport, Nav, Apps.