Doors and bonnets (hoods) are structural body panels providing vehicle access and critical protection for internal components. Doors facilitate passenger and cargo entry/exit, incorporating integrated latching mechanisms, window regulators, and weather sealing. Bonnets provide access to the engine compartment for servicing and incorporate safety features like secondary latches. These panels are commonly constructed from steel or aluminum alloys, optimized for strength, weight, and corrosion resistance. Modern designs increasingly utilize engineered polymers for specific components to reduce mass and improve impact absorption. Precise panel fit and alignment are essential for vehicle safety systems and aerodynamic performance.