An interior rearview mirror system for a vehicle includes an interior rearview mirror assembly including a reflective element having a transparent glass substrate with a transflective reflector established at a surface thereof. The transflective reflector includes at least three thin film layers, which include at least one metallic layer. The transflective reflector exhibits a substantially spectrally neutral reflectant characteristic as viewed by a driver operating a vehicle equipped with the mirror assembly. A backlit active matrix liquid crystal video display screen is disposed behind the transflective reflector. Display information passes through the glass substrate and the transflective reflector for viewing by a driver operating the equipped vehicle. At least one silicon photo sensor is configured to detect ambient light at the vehicle, and the display intensity is adjustable responsive to a sensing of ambient light by the least one silicon photo sensor.