A blind spot monitor uses radar sensors in the rear bumper to detect vehicles beside and behind you that the mirrors do not show, and lights a warning in or near the door mirror. Many systems also sound an alert if you switch on the indicator while a vehicle is there. BSM, BSD and blind spot warning are different names for the same function.
Most useful for frequent lane changes on highways and in dense two-wheeler traffic.
Checked against this source on 18 Sep 2026. Every term