A side-view mirror, also known as a wing mirror, is a mirror placed on the exterior of motor vehicles for the purposes of helping the driver see areas behind and to the sides of the vehicle, outside the driver's peripheral vision. Almost all modern cars mount their side mirrors on the doors—normally at the A-pillar—rather than the wings The side mirror is equipped for manual or remote vertical and horizontal adjustment so as to provide adequate coverage to drivers of differing height and seated position. Remote adjustment may be mechanical by means of bowden cables, or may be electric by means of geared motors. The mirror glass may also be electrically heated and may include electrochromic dimming to reduce glare to the driver from the headlamps of following vehicles. Increasingly, the side mirror incorporates the vehicle's turn signal repeaters. There is evidence to suggest mirror-mounted repeaters may be more effective than repeaters mounted in the previously predominant fender side location. ".
Optional side mirror
In the 1940s many roads were unpaved and had two lanes, one in each direction. Drivers had to be aware only of traffic on their side and directly behind them. Due to this, most passenger vehicles with an internal rear-view mirror until the late 1960s had the passenger-side mirror only as an optional addition, as it was considered a luxury.
In the U.S. and Canada, the U.S. National Highway Traffic Safety Administration's Federal Motor Vehicle Safety Standard 111 and the Canada Motor Vehicle Safety Standard 111 require the driver side mirror to provide "unit magnification", i.e., an undistorted 1:1 reflection achieved with a flat mirror. However, unit magnification limits the field of view that can be provided by a mirror of size compatible with the vehicle body. The ECE regulations in use throughout most of the world except North America permit the driver side mirror to have a planar, convex, or aspheric surface; an aspheric section is often combined with a larger convex section, and the two sections are separated by a visible line to alert the driver to the two sections' different perspective shifts. Because of the distance from the driver's eye to the passenger side mirror, a useful field of view can be achieved only with a convex or aspheric mirror. However, the convexity also the objects shown. Since such objects seem farther away than they actually are, a driver might make a maneuver such as a lane change assuming an adjacent vehicle is a safe distance behind, when in fact it is quite a bit closer. In the United States, Canada, India, Korea and Australia, non-planar mirrors are etched or printed with the warning legend. In Canada, this warning is often supplemented by a transparent decal on the passenger side window repeating the warning in French:. In Korea, the warning appears in Korean. Warnings of this nature are not required in Europe.
Other requirements
More commonly in cars manufactured since the 2000s, side mirrors may be manually or electrically folded in, to protect them when the car is parked or being washed in an automated car wash. Passing cars can easily clip protruding side mirrors; the folding capability helps protect them from harm. ECE Regulation 46 requires that side mirrors be mounted such that they swing away when struck by a test cylinder meant to represent a pedestrian. Until March 1983, the Japanese Ministry of Transport did not allow to register cars without mirrors on front fenders, so the mirrors were mounted far forward atop the front fenders. More recent Japanese-specification vehicles have side mirrors similar to those in other countries. Taxi drivers and other professional drivers retain a preference for the wing-mounted mirrors as they feel that they work better in extremely tight traffic. U.S. Federal Motor Vehicle Safety Standard 111 requires that convex side view mirrors must have a curvature radius of between 889 mm and 1651 mm. Canada Motor Vehicle Safety Standard 111 stipulates a range of between 890 mm and 1800 mm. Neither the U.S. nor the Canadian standard allows for aspheric mirrors. The European ECE Regulation 46 used throughout most of the world permits planar, convex, and/or aspheric mirrors on either side of the vehicle. American research suggests non-planar driver side mirrors may help reduce crashes.
