Delphi has developed an infrared side alert system, called Forewarn, to detect vehicles in your blind spot. It measures temperatures in the lane 10 feet to your side and 26 feet back and if it detects a vehicle it signals in your side mounted rearview mirror. The information on the company website describes the sensor system as designed for light duty vehicles but it has just shown up installed as a motorcycle alert system at the Consumer Electronics Show, now under way.
Delphi Forewarn® Infrared Side Alert is designed to help drivers be aware of vehicles in their side blind spots when changing lanes and making turns. A cost-effective safety enhancement for light-duty vehicles, passive infrared sensors integrated into mirrors, taillights or side fascia measure adjacent lane temperature over time to detect vehicles entering the side blind spot. If a vehicle is detected in the blind spot, Side Alert can help drivers avoid a lane change accident by providing a visual indication in the mirrors. When the turn signal is activated to signal a lane change, the driver also receives an audible alert.