An exterior rearview mirror assembly for a vehicle includes a mirror head portion and a reflective element accommodated by the mirror head portion. The reflective element includes a glass substrate and a mirror reflector coated at a surface of the glass substrate. The reflective element is configured to provide a field of view of at least about 15 degrees at the side of the vehicle and provides a substantially undistorted reflected image as viewed by the driver of the vehicle. The reflective element may have a width dimension of less than about 15 cm and a height dimension of less than about 9 cm. The mirror substrate is curved or formed via a hydro-bending process utilizing at least one bending element, which may be CNC formed in accordance with a free form pattern of curvatures.