A grille is a device found on a vehicle that sits directly in front of the radiator. Air flowing through the grille is allowed to pass through the radiator and maintain a cool temperature. Even the air conditioning benefits from the cool air flowing through the vehicle's grille and over the air conditioning condenser. Other areas typically containing a grille include the area directly at the base of the windshield, the side of the front fender as well as the vehicle's dash. Anywhere that air is intended to flow easily through the vehicle, there will be a grille in place.
Vehicle heaters typically draw cold air in from the cowl at the base of the windshield. This air is directed through the heater box and passed through the heater core. This warms the air charge, and it is sent into the passenger cabin or up through the defroster vents. While many vehicles take cool fresh air through a grille in the cowl, only a select few actually filter this incoming air. Some higher-end vehicles use a filter to clean the incoming air and remove irritants such as pollen.
On high-performance vehicles, a cold air charge is often taken from a front fender grill and channeled into the induction system. Engines receiving a cold air intake will produce more horsepower than a similar engine taking in a hot intake air charge from the engine compartment. Many times these air intake grille openings are not actual openings—they only appear to be. Some vehicle owners will fabricate actual openings connecting to these faux grille openings to draw cool air into the engine.
The vehicles from the 1980s and 1990s adhered to a monochromatic design theme which did away with an actual grille opening in the front of a vehicle. These vehicles took air through the radiator by directing air underneath the nose of the vehicle up and through the cooling system. These vehicles often overheated and were very susceptible to cooling problems stemming from damage to a small rubber flap under the front bumper. This flap was intended to direct the air upward through the radiator; however, it was frequently damaged by pulling too close to a curb.
Designers began to incorporate actual grille openings into vehicles in the late 1990s and some manufacturers such as Chrysler have made the opening the symbols of their companies. Chrysler's four-bar cross opening is synonymous with all of its product line. Other manufacturers have simply elected to chrome the entire area, creating a focal point in their product lines.