Light-responsive vehicle control such as an electro-optic rearview mirror system that is adaptive to vehicle configuration having a sensitivity selection

A vehicular rearview mirror system includes a control that receives inputs from ambient and glare detecting light sensors and establishes reflectance levels of the interior mirror reflective element and exterior mirror reflective element. The control includes a sensitivity selection for establishing a sensitivity level as a function of light sensed by at least one of the ambient and glare detecting light sensors. The reflectance level of the interior and/or exterior mirror reflective element is at least a function of the sensitivity level.