The phrase "main radiator" refers to the main part of a system that helps cool down or heat up something, usually by transferring heat to or from a liquid or gas passing through it. Full definition
The front spoiler is carbon fiber has a 4 line adaptive grille element, similar to the 6 line light weight main radiator grill. (topspeed.com)
The hood is further emphasized by the raised rib aligning with the main radiator grille opening. (automobilemag.com)
The main radiator in front takes air in low and expels the heated air from the core on top of the hood, where it is directed outward so it «washes» the sides and adds heat energy to the air flowing around (and through) the car. (automobilemag.com)