What Is Blind Spot Monitoring?

This advanced driver-assistance aid acts as a second set of eyes.

Andrew Ganz | 

Mar 25, 2022 | 2 min read

Mercedes

Even if you’ve adjusted your vehicle’s side mirrors just right, you may still have a blind spot and can’t see part of the adjacent lane. To fix this problem, many modern vehicles now have blind spot monitoring, which alerts the driver of objects lurking next to the car’s rear-quarter panels.

How It Works

Vehicles with this feature have at least two sensors — generally mounted behind the rear bumper or along the side of the body — to detect when a vehicle is in your blind spot. When that’s the case, a light in or near your side mirrors will illuminate. If you signal a lane change while another vehicle is on your flank, the car will warn you typically by flashing the light and sounding a chime. Some manufacturers (e.g., Hyundai, and Kia) use a high-resolution camera to project a live feed of the driver’s blind spot in the instrument cluster or infotainment display when the turn signal is active.

Most of these systems won’t intervene to prevent impact, but some can. Cars equipped with Mercedes’s Active Blind Spot Assist, like the E-Class for instance, will try to keep you from entering another vehicle’s path by applying the brakes on the opposite side of the car. Should the driver ignore this and continue to move over, the car may attempt to mitigate the collision with steering inputs. On certain full-size pickups, blind-spot monitoring may extend to cover the area next to an attached trailer as well as the truck itself.

What Cars Have Blind Spot Monitoring?

In the mid-2000s, Volvo became the first manufacturer to offer the technology in a production car. Since then, blind-spot monitoring has become widely available. For the 2022 model year, nearly all new vehicles either include it as a standard feature or offer it as an option.

Does Blind Spot Monitoring Increase Safety?

This driver-assistance feature can make a big difference when it comes to safety. In a 2017 study, the Insurance Institute for Highway Safety reported that blind-spot monitoring reduced lane-change-related crashes by 14%. Even with careful seat and mirror adjustment, it can be difficult for drivers to eliminate blind spots. New cars have thick pillars designed to improve impact safety and wide headrests to mitigate the risk of whiplash. Those two features — as well as shrinking glass areas for the sake of styling — conspire to reduce outward visibility.