Active grille shutters
Car engines are most inefficient when they are cold. Active grille shutters help engines warm up faster by closing off the air that comes through the grille and flows through the radiator. This enables the coolant to warm up faster. Active grille shutters, available on such vehicles as the Chevrolet Cruze (pictured above), Cadillac ATS and certain version of the Ford Fiesta, also help improve aerodynamic efficiency.