Yes, that mount you have is for the BMW (Garmin manufactured) ) Navigator 4. Only the Garmin 660 and 665 and the BMW branded Navigator 4 will work in that mount. The four buttons on the left will NOT work with any GPS other than the BMW branded Navigator 4, because the firmware (embedded software) on the BMW unit is specially configured to support those 4 buttons, which are there to make it easier to use the GPS with gloves on.
There are some issues with getting sound (audio) out of that mount. I have no other information.