pattern from horizontal bars to various patterns of crosshatching as a simple way of making the car look new from year to year, for this make did not have a standard grille form. Sometimes there is a sort of fashion trend in grille bars. For example, in the early years after World War II, many American car makers generally switched to fewer and thicker grille bars. A billet grille is an aftermarket part that is used to enhance the style or function of the original OEM grille. They are generally made from billet, solid bar stock aircraft-grade aluminum, although some are CNC machined from one solid sheet of aluminum. Active Air Flap System was developed by Hyundai Mobis on June 17, 2021. Based on the existing radiator grille, the grille itself has evolved to move according to the cooling water temperature. When the engine coolant temperature is high, the air flap is opened to increase cooling efficiency through air suction. On the contrary, when the temperature drops, the air flap is automatically closed to reduce air resistance to increase fuel efficiency and electricity consumption. Customizers would alter the grille as a matter of course in personalizing their car, taking the grille bar from another make, for example. Even sheet metal with patterned holes for ventilation grating sold to homeowners for repair has been found filling the grille opening of custom cars. Grille types Per mounting location on the car body: Radiator grille (front engine vehicle); Roof or trunk grilles (rear engine vehicles); Bumper skirt grilles (front and rear); Fender grilles (brake ventilation duct covers); Hood scoop grille (to allow intercooler air flow) Per style The American aftermarket restyling industry defines two major grille styles: OEM factory-style grilles – Such grilles have no difference with those manufactured by the automobile producers; Custom style – produced in small quantities and have an assortment of materials. Per fastening method Bolt over style In this installation method, the billet grille simply bolts over the existing OEM plastic grille. This method does not require drilling or cutting of the OEM grille shell. Hidden bolts, brackets and clamps are used for this simple installation. The downside is it may not look as clean as the replacement style, because you can still see the OEM grille underneath. Bolt overs should take no more than 30 minutes to install. Replacement style The OEM grille must first be removed