An interior rearview mirror system for a vehicle includes a mirror assembly having a variable reflectance element. The variable reflectance element includes a metallic mirror reflector on one side of a substrate, with the metallic mirror reflector being partially transmissive to visible light. The interior rearview mirror assembly includes an information display positioned to the rear of the metallic mirror reflector, wherein the information display emits light that transmits through the metallic mirror reflector for viewing by the driver of the vehicle. Responsive to a light level sensed by at least one light sensor, the luminous intensity of the information display is adjustable by a control to provide a luminous intensity of at least about 750 candelas/sq. meter to a driver of the vehicle viewing the information display through the metallic mirror reflector of the interior rearview mirror assembly when it is normally mounted in the vehicle.