A new air-conditioning system for hybrid cars keeps cool air coming even when the engine shuts off. The system, called Stop-Stay-Cool from German developer Valeo, works with the company's starter-alternator. The belt-driven starter-alternator generates electricity when the engine is running and starts the engine, eliminating a separate starter motor.

The new air-conditioning system works similar to a fan passing air over a block of ice. Climate-control engineers at Valeo developed a proprietary material said to have ideal thermal qualities for automotive evaporators. The new evaporator stores cold energy during normal engine operation and releases it to the ventilation system when the AC compressor kicks off.