A bottle-shaped, low-drag air intake design.
A design for a low restriction air inlet developed by the National Advisory Committee for Aeronautics, it is often seen on race cars, but was also used on the hoods of 1987 Callaway Twin Turbo Corvettes and on some one-off Corvette showcars.
This is an air opening which was named after the National Advisory Committee for Aerodynamics. It was the American organization which developed the kinds of designs for low drag air ducts for jet engines. NACA ducts are used on cars to force air for engine breathing and cooling, for forcing air through the radiators, and for providing fresh air for the passenger compartment.