- Inventor
- Mercedes-Benz (Pre-Safe Brake) and Volvo (City Safety) engineering teams
- First used
- 2006 — Mercedes-Benz S-Class (W221) with Pre-Safe Brake; 2008 — Volvo XC60 with low-speed City Safety as standard
- Origin
- Germany and Sweden
How it came to be
Mercedes-Benz introduced 'Pre-Safe Brake' on the 2006 S-Class — radar-based, autonomously braking at up to 40% deceleration if the driver ignored warnings. Volvo democratized the technology in 2008 by making 'City Safety' standard on the XC60, working at urban speeds with a windscreen-mounted lidar. Subaru followed with stereo-camera EyeSight in 2010. By the mid-2010s, IIHS testing and Euro NCAP star ratings effectively forced AEB onto every new car, and 20 major automakers voluntarily agreed in 2016 to make it standard in the US by September 2022.
Key milestones
- 2003Honda Inspire introduces Collision Mitigation Braking System (CMBS), the first AEB precursor.
- 2006Mercedes S-Class launches Pre-Safe Brake — first true autonomous emergency brake.
- 2008Volvo XC60 makes low-speed City Safety standard equipment.
- 2010Subaru EyeSight brings stereo-camera AEB to the mainstream.
- 201620 automakers and the US DOT agree to make AEB standard by 2022.
- 2022EU mandates AEB with pedestrian and cyclist detection on all new car types.
- 2029Planned US NHTSA rule requires pedestrian-detecting AEB on all new light vehicles (proposed).
EU General Safety Regulation requires AEB with vulnerable-road-user detection on all new car types from July 2022. The US is finalising a similar federal standard (FMVSS 127) for the late 2020s.
How it triggers
Forward-facing radar (typically behind the badge) and a camera measure the closing rate on cars, pedestrians and cyclists ahead. If a collision becomes likely, the system first warns you (audio + visual), then pre-charges the brakes. If you still don't react, it applies full braking automatically.
Speeds it works at
Modern systems (Volvo City Safety, Subaru EyeSight, Toyota Safety Sense 3.0) work from about 3 mph up to highway speeds. Below 25 mph they often stop completely; above that they reduce impact speed dramatically rather than fully preventing the crash.
Pedestrian and cyclist detection
Newer cameras can identify pedestrians day and night, plus cyclists from any angle. Mandatory in the EU since 2024 on new car types. IIHS testing shows the best systems prevent 50%+ of forward collisions and reduce crash severity in most of the rest.
What can fool it
Dirty sensors, heavy precipitation, low-contrast clothing at night, and odd geometries (a car parked perpendicular across your lane) all reduce reliability. Cross-traffic AEB (some Mercedes, Volvo, BMW) extends the system to T-intersections.
