Predictive Emergency Braking (PEB) is a safety system which aims to prevent rear-end collisions.
PEB senses when a collision is becoming likely. It first informs the driver with a warning chime, then if the driver does not intervene the system automatically applies heavy braking to avoid or minimise a collision. PEB deliberately uses as much of the remaining braking distance as possible, rather than stopping the car in the smallest possible space, to give more space for following vehicles to stop.
The video above demonstrates the Bosch adaptive cruise control and predictive emergency braking on the Audi A6.