Cooling Film for auto Windows

What a neat idea. Now I'd like to know if the film can be applied to older autos or must all auto glass be replaced with the new product? What about the film being used on buildings? -----BumbleBeeBoogie

BELLS & WHISTLES
Cooling Film for Windows
By JOYCE COHEN - New York Times 4/2/03

Sure, a bulky cardboard shade propped in the windshield will help keep a parked car from heating up like an oven in the summer sun. But 3M has come up with something way cooler, Solar Reflecting Film, an ultrathin sheet of clear plastic built into the windshield. It deflects the sun's heat and ultimately increases fuel efficiency.

The invisible film, sandwiched in the windshield's layers of glass and plastic, is on the rear windshield of the BMW 7 series and the Porsche Cayenne. In the next model year, more brands and models will have the film. Its use will be expanded to front windshields and, possibly, side windows, said Doug Thompson, business director in the automotive division of 3M.

The film does not just keep the car cooler in the sun, but it also works while the car is moving, reducing the burden on air-conditioners and raising fuel economy up to 0.3 miles a gallon, Mr. Thompson said. He added that concern about gasoline consumption was growing as designers seek to add glass on cars. The film helps manage the solar energy load.

Previous attempts to screen out the bright sun relied on metal-based coatings that reduced visibility and interfered with electronic signals like those used for mobile telephones, garage-door openers and toll passes. Now, 3M hopes to expand the use of its film to windows for buses, trains and ships.