Dozens of children are thought to die worldwide every year from being left alone in hot cars, and in a bid to save lives Swedish manufacturer Volvo has announced a new passenger detection system. Volvo said it will be the first carmaker to equip vehicles with radars mounted on the ceiling throughout the car. The devices detect tiny movements such as the breathing of a sleeping toddler and sound the alarm if they are locked inside. It is the first such feature to cover the entire interior of the car, including the boot, said the carmaker, known for incorporating advanced safety features. The up…