An interior rearview mirror system for a vehicle includes an interior rearview mirror assembly having a mirror housing, a transflective reflective element, a compass sensor and compass circuitry. An information display is disposed in the mirror housing rearward of a transflective mirror reflector of the reflective element, and information displayed by the information display is viewable by a driver of the equipped vehicle through the transflective minor reflector of the reflective element when the information display is displaying information. The compass sensor may be disposed in the mirror housing rearward of the reflective element. The compass circuitry may be responsive to the compass sensor for determining a directional heading of the vehicle. The information display is operable to display the directional heading to the driver of equipped vehicle. The compass circuitry at least partially compensates for movement of the compass sensor caused by adjustment of the mirror housing.