"Bonnet vents" refer to small openings or slits on the hood (bonnet) of a vehicle. They are designed to let air flow through the engine compartment, helping to cool down the engine and prevent overheating. Full definition
The Japanese model also sports a tailgate mounted spare wheel, signal lamps incorporated into the side mirrors but also a pair of bonnet vents mounted on each side. (automotorblog.com)
Black bonnet vents and yellow / blue stripe make it easy to spot. (evo.co.uk)
Despite the many exterior similarities between the V8 «S» and V12, the S has not inherited the four large air bonnet vents. (astonmartins.com)