Guide to Automatic Emergency Braking

We’re often asked, “Is AEB the same thing as ABS?” Both technologies have to do with braking, but that’s where the similarity ends. antilock braking systems (ABS) use wheel sensors to maximize braking action and prevent wheels from locking up and a car from skidding. It requires the driver to hit the brakes. But if a car equipped with AEB senses an imminent collision and the driver doesn’t react in time, the car starts braking on its own. Some systems apply only a portion of the braking power, so drivers will want to apply the full brakes as well. Data from the Insurance Institute for Highway Safety (IIHS) shows that rear-end collisions are cut by 50 percent for vehicles equipped with AEB and forward collision warning (FCW).

Nearly all new vehicles on sale today have some form of AEB. A new rule from the National Highway Traffic Safety Administration (NHTSA) will require passenger vehicles by September 2029 to have AEB that can avoid a crash with a vehicle in front at speeds of up to 65 mph, reduce the effects of a crash at speeds of up to 90 mph, and avoid a crash with a pedestrian in both darkness and daylight at speeds of up to 45 mph. NHTSA says the new rule could save over 360 lives and prevent over 24,000 injuries each year.

Until the rule goes into effect, several kinds of AEB exist on modern vehicles.

Common Variations
Automatic emergency braking (AEB): Detects potential collisions with a vehicle ahead, provides a forward collision warning, and automatically brakes to avoid the collision or lessen the severity of impact. 

Automatic emergency braking with pedestrian detection (AEB-ped): Detects potential collisions with pedestrians or bicyclists while the car is traveling forward and automatically brakes to avoid the collision or lessen the severity of impact. 

Some AEB systems operate only at city speeds, which are typically at 55 mph and below. Other AEB systems can work at highway speeds, which are typically above 55 mph.

Rear automatic emergency braking (AEB-rear): Brakes are automatically applied to prevent a collision or reduce impact force while the car is traveling in Reverse.

In our most recent survey, we asked CR members to rate their experiences with the advanced safety and driver-assistance systems on their 2017-2022 cars. Respondents answered questions about their satisfaction with the systems. The survey covered about 47,000 vehicles.