High-tech shutters on new cars are mechanisms that are sandwiched between the car’s grille and radiator and are controlled by the car’s engine computer. The computer uses several factors to decide whether the shutter slats should be open, closed or somewhere in between. When open, the car can breathe better on hot days or under stress. When closed, the car becomes more aerodynamic, trapping or disrupting less air and increasing fuel mileage up to 2%.