No, the lowest speaker in the X5 is by the window switches and mirror controls, unless you count the subwoofer. It is definitely another speaker not a part of the 14-speakers + 2 sub setup. Also, the car was stopped and I felt + saw the speaker in there. I can take a picture of the footwell speaker if you'd like.

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2012 BMW X5 xDrive35d
Alpine White | Sand Beige Nappa w/ Leather Dashboard | Light Poplar | Premium Pkg | Sport Pkg | Premium Audio Pkg | Tech Pkg w/ HUD | Multi-Contour Seats | Heated Seats | 20" Wheels | Soft-close Doors | Running Boards | Spare