Laser scanners will make sensor-driven safety systems more accurate still. Take BMW's Left Turn Assist, which the company revealed earlier this year but hasn't yet slated for production. Left Turn Assist uses a trio of laser scanners, along with a lane-detecting video camera and GPS, to make left turns—statistically one of the most dangerous maneuvers on the road—safer. When a computer senses that the driver is about to take a left, lasers scan a 200-degree field for hazards. If the system detects an imminent threat, and the car is moving slower than 6 mph, it will brake automatically. At higher speeds, it triggers audio and visual alarms. Laser scanners are still prohibitively expensive, says Dirk Wisselman, BMW's head of Advanced Safety Systems, but the cost is falling quickly.