What is the panel below the car door called

The panel below the car door is called the door sill or rocker panel. It forms the lower part of the door frame, running along the length of the vehicle between the front and rear wheels. Door sills serve both structural and aesthetic purposes, protecting the car’s underbody from debris and providing a step for entering or exiting. Some models, like the BMW iX or Range Rover, feature illuminated or reinforced sills for added durability and style.

Door sills can be made from steel, aluminium, or plastic, depending on the vehicle’s design. Over time, they may suffer scratches or rust, especially in areas with road salt. To maintain them:

1. Clean regularly to remove dirt and salt buildup.
2. Apply a protective wax or sealant to prevent corrosion.
3. Check for damage after off-road driving or impacts.

In premium cars, sills often bear branding (e.g., "Mercedes-Benz" embossed). Aftermarket options exist for customisation, including stainless steel covers or LED-lit versions.

The panel below the car door is called a side skirt. It is also referred to as a rocker panel or lower sill. The side skirt is a panel installed along the sides of the vehicle body, functioning similarly to an air dam to reduce airflow entering beneath the car from the sides. It provides a degree of aerodynamic interference and can significantly reduce air resistance under certain conditions. The side skirt is part of the vehicle's aerodynamic spoiler kit and, when properly fitted, can minimise reverse airflow generated during driving. At high speeds, it creates a ground effect, substantially improving handling stability.

Materials used for car side skirts: Generally, they can be categorised into three types: single-piece pressed steel, engineering plastic, and single-piece pressed aluminium alloy.

Common door accessories:

1. Door window: Provides the driver with a degree of lateral visibility to aid driving.
2. Door hinge: Supports the door and ensures smooth opening and closing.
3. Door handle: The interior handle is typically fixed to the door trim panel, while the exterior handle is mounted on the door outer panel, facilitating door operation.
4. Door check strap: Limits the maximum opening angle of the door, ensuring it stops at a certain position to assist passengers when entering or exiting the vehicle.

From a repair technician’s perspective: the panel beneath the door is the rocker panel. It’s a critical structural component, often welded to the chassis. Damage here can compromise safety, so inspect it during MOT checks. Rust is common—especially in older Vauxhall Corsas—so treat any corrosion early. Replacement parts vary by model; a Ford Focus sill differs from a Tesla Model 3’s aluminium design.