A car door is a type of door, typically hinged, but sometimes attached by other mechanisms such as tracks, in front of an opening which is used for entering and exiting a vehicle. A vehicle door can be opened to provide access to the opening, or closed to secure it. These doors can be opened manually, or powered electronically. Powered doors are usually found on minivans, high-end cars, or modified cars.
General design
Unlike other types of doors, the exterior side of the vehicle door contrasts in its design and finish from its interior side or a door panel that has decorative and functional features. The exterior side of the door is designed of steel or other material like the rest of the vehicle's exterior. In addition, its decorative appearance, typically colored with a design, is intended to match with the rest of the vehicle's exterior, the central purpose being to add to the overall aesthetic appeal of the vehicle exterior. A vehicle typically has two types of doors: front doors and rear doors. Loosely related are: vehicle hoods and vehicle trunk lids. There are also doors known as a "hatch" A major safety issue with opened vehicle doors is the assumption at night vehicle doors can provide a warning to other vehicle drivers. Unfortunately it is estimated over 50 percent of all vehicle doors have nothing applied to the interior of the vehicle door such as light and/or a reflector. Unfortunately these devices need not meet any US Federal Motor Vehicle Safety Standards since no standards apply. To make matters worse it was reported by the Fatal Accident Reporting System that in the year 2014 not one single death was reported with a person outside the opened vehicle door at night in the entire United States of America. New safety technology such as providing to the lower interior edge of the vehicle door a highly reflective tape provides the ability of other vehicle drivers to see the opened vehicle door at night
Most vehicle doors are secured closed to the vehicle body with latches which may be locked to prevent unauthorized access from the exterior. There are a variety of car door locking systems. Door locks may be manually, or automatically operated, and may be centrally or individually operated. Also, they may be operated by remote control, with the transmitter often integrated into the main vehicle access / ignition key. Additionally, rear passenger doors are frequently fitted with child safety locks to prevent children from exiting the vehicle unless the door is opened from the exterior. These are also frequently used on police cars, to prevent suspect criminals from escaping whilst in police custody. Vehicle door latches on practically all vehicles today are usually operated by use of a handle which requires the user to pull, lift, or tug - with some force towards themselves rather than push. There is a reason for this. As late as the 1970s, some vehicles used exposed push buttons to operate the door latch, such as certain Opel models. The unfortunate side effect of this design was that external objects which touched a vehicle during a spinout could trigger the latch; the door would pop open and eject the vehicle occupants. A death which occurred exactly that way led to the landmark legal case of Daly v. General Motors Corp., , in which the Supreme Court of California merged strict product liability with comparative fault, and thereby affirmed the right of General Motors to introduce evidence that decedent Kirk Daly flew out of his Opel not only because the door popped open, but because he was intoxicated and not wearing a seat belt.
Door switch
Door switches are simple on/off mechanisms connected to the interior light, and may also be connected to a warning light, speaker or other device, to inform the driver when the door is not closed. The door light is standard equipment on all cars. In American cars from the 1950s-1990s, they had buzzers or "door dingers" that sounded, along with the check light, whenever any door is open.
Windows
Most vehicle doors have windows, and most of these may be opened to various extents. Most car door windows retract downwards into the body of the doors, and are opened either with a manual crank, or switchable electrical motor. In the past, certain retracting windows were operated by direct pressure, and were held in the up position by friction instead of by an internal lift mechanism. Other cars, particularly older US-manufactured vans, have hinged windows with a folded lever mechanism to push and hold the window out from its closed position.
Door brakes or stays
Vehicle doors often include brakes, or 'stays', that slow the door down just before it closes, and also prevent the door opening further than its design specification. The current trend is to have a three-stage door brake. Door brakes exist because the doors on the first vehicles were heavy, so they had to be pushed hard to make them close. Soon after, automotive manufacturers managed to construct lighter doors, but users were used to closing doors with force so doors quickly became damaged. Door brakes were then introduced to slow down the door just before the door closed to prevent damage; these soon became standard.
Door categorization
and estate or station wagon bodies are sold as 'three-door' or 'five-door' models. In these cases, the rear hatch is classified as a door; this is because it enters the passenger compartment. With other vehicles such as saloons or sedans and coupés, the boot/trunk lid is not counted as a door by definition because it is for a separate storage compartment - these cars are sold as 'two-door' or 'four-door'. This system is mainly used in Europe, and is less common in North America. In Europe, the American-style labelling is occasionally used. Usually in North America, cars are only sold as "two-door" or "four-door" models. This American-style labelling only includes the passengers' and driver's doors, and not hatches on hatchbacks and station wagons. This has led to many not understanding that hatches are counted as doors in Europe, whilst the lids to sealed trunks aren't.
Being doored
Some cyclists refer to colliding with an open car door as "being door checked". This usually happens when the cyclist is riding alongside a row of parallel-parked cars, and a driver suddenly opens his or her door immediately in front of the cyclist without first looking to see if it is safe to do so. Major advancements have been made to allow visual recognition of a partially opened vehicle door to provide a degree of warning to cyclists and motor vehicle drivers particularly at night. See US Patent No. 9,469,246.
Types
There are many different types of vehicle doors, including the following:
Conventional
A conventional door, also known as a regular door is hinged at the front-facing edge of the door, and so allows the door to swing outward from the body of the car. These doors are relatively safe, in that if they are opened during forward motion of the vehicle, the wind resistance will work against the opening door, and will effectively force its closure. The operation of a vehicle door entering, exiting, or standing out side an opened vehicle door is extremely dangerous particularly at night even when looking both ways. The issue is the vehicle door in most cases provides not visual warning to other vehicle drivers to allow accident avoidance of another vehicle driver to have the time to take avoidance measures. New advancements have been made to allow the viewing of the opened vehicle door at night with the addition of highly reflective tape applied to the lower interior edge of the vehicle door. These new advancements allow the opened vehicle door to be seen even with a person blocking the prior art systems such as a reflector or a light by providing reflex reflectivity exceeding fifty percent of the vehicle door behind a person legs blocking the opened vehicle door at night.
Suicide
A suicide door is hinged on its trailing edge. The term "suicide door" was coined due to the potential for the door to fly open when the latch was released while car was in motion.
Scissor
Scissor doors rotate vertically upward and are hinged at or near the end of the windshield. They are used in Lamborghinis, Alfa Romeos, and other brands.
Butterfly
Butterfly doors are similar to scissor doors, but while scissor doors move up, butterfly doors also move outwards, which makes for easier entry/exit, and saves space.
Gull-wing
Gull-wing doors are hinged on their uppermost edge, at the roof rather than the side. They are so named because, when opened, the doors evoke the image of a seagull opening its wings.
Sliding
Sliding doors open by sliding horizontally or vertically, whereby the door is either mounted on, or suspended from a track. They are commonly used on the sides of minivans, leisure activity vehicles, light commercial vehicles, minibuses and some buses as this allows a large opening for equipment to be loaded and unloaded without obstructing access.
Canopy
A canopy door sits on top of a car and lifts up in some way, to provide access for passengers. It is similar to an aircraft canopy. There are no set standards to canopies, so they can be hinged at the front, side or back - although hinging at the front is most common. Canopy doors are rarely used on production cars, but are frequently used on the 'closed' variants of Le Mans Prototype endurance race cars. They are also sometimes used on concept cars.
Disappearing
A disappearing door slides down and under the vehicle. This type makes the whole side of the passenger compartment open, and only leaves a threshold to step over to get in and out. Also called the Jatech rotary drop door, or disappearing car door. One example of a car with disappearing doors is the Lincoln Mark VIIIconcept car.
