Besides cooling interiors, such "fan systems" could help fuel efficiency since most drivers blast their air-conditioning after the car has been sitting under the sun for some time. A parked-car cooling system would lessen that need. Also, automakers would not need to build such powerful AC units, thereby reducing the parasitic load on the engine and lightening the vehicle overall, which in turn improves fuel-efficiency. The Society of Automotive Engineers is currently testing vehicles equipped with new solar-powered fans as well as heat-reflective glass and paint to measure the impact of interior heat on mileage.
[Source: Los Angeles Times via Detroit News]