What is AEB?

Automatic Emergency Braking is now very common and it can undoubtedly save your life - but how does AEB work?

BuyaCar team
Jun 14, 2021

Car safety is a field that is always progressing, although some more basic equipment such as seatbelts and airbags have existed for decades, there are now a number of new, far more advanced safety systems that feature on most, if not all cars made today.

One of the latest systems to be rolled out is Autonomous Emergency Braking (AEB). This is a computer-based system that constantly monitors the space ahead of the car using radars and cameras, in order to sense approaching obstacles. If the system detects a hazard, it warns the driver and will often apply the brakes or supplement the driver's braking.

Let's explore what it means:

Autonomous - a system that acts without the active input of a driver
Emergency - it will only intervene when it deems that you're on course for a collision
Braking - the system will apply the brakes

As with many new technologies, AEB was once reserved for more expensive cars, but it is now finding home in smaller and more affordable cars. Read on for more details on how Autonomous Emergency Braking works.

Why buy a car with AEB?

AEB can act as a safety net in an emergency. You might think that you’ll never need it, but there are often factors outside of your control that can affect your judgement or require a faster reaction than a human is capable of. Car manufacturers cite poor visibility and glare from sunshine as major reasons for the take-up of AEB in their cars.

Of course, AEB systems are not fool-proof, and no carmakers are saying that it will stop all accidents. But it has been scientifically proven to assist in avoiding accidents, as well as reducing the severity of them.

How does AEB work?

AEB systems use a selection of devices to ‘read’ the road ahead. Most use a radar system teamed with a front facing camera, usually attached to the nose of the car. Many manufacturers are turning away from shiny metal badges to flatter, plastic alternatives, as these double up as the housing for the sensors required for this technology.

From behind the wheel, the first sign of the system working will usually be an on-screen prompt via the dashboard, alerting you to the fact that it thinks you’re about to hit something. If you don’t use the brakes or turn the steering wheel, the car will apply its brakes automatically.

Braking power and ferocity varies from manufacturer to manufacturer, and some of them will deactivate once you use the brakes.

Obviously, manufacturers, along with safety experts, do not recommend relying on AEB instead of your own right foot. AEB doesn’t kick in until the very last moment, and it’s a strong and harsh system that you wouldn’t want to use in everyday traffic.

In general, the more expensive systems work up to a higher speed than cheaper systems. Most accidents occur in city driving at around 12-15mph and most AEB systems work at up to 25mph, but some work at motorway speeds too.

AEB Safety testing

Euro NCAP is a safety assessment program that every new car in Europe has to be put through. It awards cars on a star-based system, the safest cars get five stars, the most unsafe get zero.

Not only do AEB systems make a car safer for the occupants, but it’s proven to make them much safer for pedestrians. Pedestrians and cyclists account for 30% of all fatalities in the EU every year. Because of this, pedestrian and cyclist safety is a growing concern for Euro NCAP.

One of the criterias on which new cars are assessed is a pedestrian test. This is designed to check how well pedestrian-detection systems work. The tests represent common situations that cause pedestrian casualties. In these simulations, generally, when an AEB system is used, accidents that would normally result in a fatal collision can be avoided.

Safest cars in 2021/22

Euro NCAP asseses cars based on four factors: adult occupant protection, child occupant protection, vulnerable road user protection and safety assist systems. Below are some of the safest cars tested under the most recent iteration of the testing procedures.

Skoda Enyaq

Adult: 94%
Child: 89%
Pedestrian: 71%
Safety: 82%

Used deals Limited stock

Polestar 2

Adult: 93%
Child: 89%
Pedestrian: 89%
Safety: 86%

Used deals Limited stock

Volkswagen ID.4

Adult: 93%
Child: 89%
Pedestrian: 76%
Safety: 85%

Used deals from £40,000
Monthly finance from £618*

AEB benefits

Autonomous Emergency Braking can save lives, particularly when a driver might be momentarily distracted at the wrong time. Generally, the system makes the car safer: better for you, and better for pedestrians. As a result of this added safety, it can also make insurance cheaper. 

AEB drawbacks

Obviously, the safety benefits far outweigh the drawbacks of such systems. However, if you’re the type of person that doesn’t like electronic systems interfering with your driving, AEB might irk you.

Each manufacturer's system works differently, and some don’t like you getting too close to the car in front during motorway driving. Cheaper systems can sometimes get confused between pedestrians and other cars in traffic.

Which cars have AEB?

The vast majority of new cars being made today now feature AEB either as standard or as an option. It is worth noting that not all models of the same generation necessarily offer the same safety kit - sometimes manufacturers introduce these updates halfway through a car's life. To be sure, consult the specific vehicle's spec sheet or contact the manufacturer.


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