What is the bonnet/what does it do?
The bonnet is a crucial part of the car body, for beneath it is housed some of the most important components a car needs in order to run. In most cars the bonnet is the hinged cover that protects and allows access to the engine compartment. In some cars, such as the VW Beetle, however, the engine is positioned in the rear of the vehicle, so the bonnet would, in this case, give access to the space designated for luggage.
Getting into the details of the bonnet
Often made of steel, bonnets are also made of aluminum, fibreglass, dry carbon and carbon fiber. The bonnet is fixed to the frame at the front of the car and, with the action of hinges, opens outwards. A bonnet is made up of an outer panel which is designed to be smooth and streamlined, assisting with the aerodynamics of the vehicle, contoured to match the shape of the car, and an inner panel which is strong and offers protection to the engine beneath.
The bonnet usually works with a latch mechanism. It's held down by a latch which stops it from opening unexpectedly while driving along and also acts as a lock. The bonnet can be opened from the exterior, by releasing the latch, hidden just under the bonnet lip, or by pulling a small lever inside the car, usually located beneath the steering wheel, which is attached to the bonnet pull cable, which causes the bonnet to pop open. The bonnet can be held up and in place with the aid of a hinged rod, commonly referred to as a stay rod, or by a gas strut. Some bonnets, particularly aftermarket ones, are held down and kept shut with pins.
Many car owners choose the bonnet as a feature to customise. Some bonnets may have a mascot, ornament, badge or emblem mounted on to them, which is often the car manufacturer's symbol. Some cars have a bonnet scoop or power bulge; a raised part which assists with air flow to the engine, and also functions to allow room for engine and air filters, for example. Bonnet scoops and power bulges are often purely decorative, largely fitted to personalise and enhance the look of the vehicle. Some bonnets will also house wiper/washer jets, fitted to provide a directed burst of spray to clean the windscreen of the car. Many car owners choose to fit bonnet insulation which primarily helps to reduce the noise produced by the engine. Bonnet insulation absorbs both noise from the engine and the road before it reaches the inside of the car. Some bonnets will have grilles, meshes and vents, designed to assist with air flow and cooling of the engine.
What if something goes wrong with the bonnet?
Subject to damage from scratches, scrapes and dents, and damage caused by stones and other unwanted objects flying up from the road, as well as being exposed to all weather conditions, the outer panel of the bonnet can, over time, look a little worse for wear. Issues can arise from a dirt build up on the bonnet latch mechanism, leading to a bonnet that sticks and is hard to open. In some cases the bonnet may not open at all due to a faulty or worn out mechanism, perhaps with the bonnet pull cable that attaches to the latch mechanism. You may need to replace the bonnet because it has suffered damage in a crash. Some car owners merely want to give their car a new look and buying a bonnet manufactured to fit the make and model of your car will ensure the part fits and performs properly.