With respect to "One (1) set A/V input for auxiliary Audio/video devices" the GPS might switch to AV display automatically once AV is present at this input (hands free). So if the reversing camera is tied to the reversing lights (using a relay to switch 12volt to the camera based on reversing light activation), the rear view will appear auto magically on the GPS . . . maybe. Other units I have looked into do this.

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X3 E83 2006 3.0d