These devices, known as pre-crash safety systems, are technologies that detect imminent dangers (i.e., crashes), priming the vehicle’s safety equipment to prepare for impact. An example of this would be pyrotechnic seat-belt pre-tensioners, which cinch a car's three-point harnesses before impact.
Each automaker has a different approach with their technology. Mercedes' S-class “Pre-Safe” system automatically closes an open sunroof and moves front and rear passenger seats to their safest positions. The Lexus GS Pre-Collision Safety (PCS) System uses radar to keep track of obstacles and if it determines a collision is unavoidable, tightens all driver and passenger seat belts while maximizing braking power.
Finally, Honda Motor Co.’s Accord uses a camera that sends a signal to the car’s power steering if it senses the car drifting from its lane.