Active Protection is a security technology that BMW automobile manufacturers propaganda. After
starting vehicle (vehicle speed above 18 km / h) immediately enable proactive protection, automatic fine-tuning and fasten your seat belts. When it detects a risk of collision ahead by radar, or if there are strong indications that the vehicle sensors when skidding occurs, it will fully assist the driver starts braking system. If the situation is very dangerous driving, the system will increase the tension in the front seat belts, while closing the side windows and sunroof.
If a collision is unavoidable, the system will automatically apply the vehicle brake system to stop the vehicle immediately. In this way you can reduce (or completely eliminated in the ideal case) or twice the likelihood of subsequent collisions and its adverse consequences
References BMW official site