Innovation: New model shades

MERCEDES is prototyping a car sun-roof which changes from clear to tinted at the flick of a switch. It is made out of two layers of glass with an electrochromic polymer sandwiched between them. When an electric current is applied, the polymer is oxidised, changing its colour from clear, through green, to blue-black. This colour change is reversible. Experiments show that on a hot summer day, the tinting can cut the temperature in the interior of the car by 10C.