An accessory system suitable for use in a vehicle includes an interior rearview mirror assembly having a mirror-mounting portion that is adapted to detachably mount the interior rearview mirror assembly at an interior portion of the vehicle. A windshield accessory module assembly is also preferably included attached at the windshield of the vehicle. The windshield accessory module assembly is unaffected by adjustment of the rearward field of view of the reflective element of the interior rearview mirror assembly and preferably comprises at least one of a forward facing imaging device with a field of view forward of the vehicle through the windshield of the vehicle and an interior cabin imaging device with a field of view encompassing at least a portion of the interior cabin of the vehicle. The accessory system preferably includes a video display screen displaying an image captured by an image capture device with a field of view rearward of the vehicle.