Radars, cameras, or other sensors are used by forward-collision warning systems to scan the area in front of your car and then warn if they calculate that you’re closing in too fast on a car.
Using a miniature camera installed behind the inside mirror and a small display with a built in speaker that mounts to the dash, the system gives audible and visual warnings if you are following too closely, begin leaving your lane without signaling, or are approaching a pedestrian or bicyclist. It can even read speed-limit signs, monitoring your speed, and dip your high beams automatically.
Collision avoidance features are rapidly making their way into the new vehicle fleet. In a study of police-reported crashes, automatic emergency braking was found to reduce the incidence of rear-end crashes by 39 percent. A 2012 study suggests that if all cars feature the system, it will reduce accidents by up to 27 percent and save up to 8,000 lives per year just on European roads.
Unfortunately automatic emergency braking can’t be installed as an aftermarket solution for now, but the audible and visual warnings are helping the driver to take action faster.