Tractor & Construction Plant Wiki

A glossary of terms relating to automotive design.

Some terms may be found at car classification.



One-Box form
A categorization based on overall form design using rough rectangle volumes. In the case of the One-Box, also called a monospace or monovolume,[1] it is a single continuous volume. Slight wedge formed front or rear are still generally placed in this category. e.g., Bus, original Ford Econoline. The equivalent French term is volume, which you will sometimes see used by the British: "1-volume form".
Two-box form
A categorization based on overall form design using rough rectangle volumes. In the case of the Two-box form, there is usually a "box" representing a separate volume from the a-pillar forward and second box making up the rest. e.g., Station Wagon, Shooting-brake, Scion xB (2006) The equivalent French term is volume, which you will sometimes see used by the British: "2-volume form".
Three-box form
A categorization based on overall form design using rough rectangle volumes. In the case of the Three-box form, there is a "box" delineating a separate volume from the a-pillar forward, a second box comprising the passenger volume, and third box comprising the trunk area — e.g., a Sedan. The equivalent French term is volume, which you will sometimes see used by the British: "3-volume form".


The line running over the car, from headlight to taillight, tracing the car's silhouette.
Axis-to-dash ratio
The critical relationship between front wheels and the windshield. The most notable differences can be seen between cars with front-engine, front-wheel drive layout and front mid-engine, rear-wheel drive layout: the former tend to have longer front overhangs with a smaller axis-to-dash ratios, while the latter have shorter front overhangs with much greater axis-to-dash ratios.


The rear glass window glass.
The line going from the hood which usually follows the bottom edge of the windows and continues to the trunk. The beltline is a major component of the vehicle's overall appearance, as well as the safety aspect of blind spots.
(contemporary) See brightwork. May also refer to the strong use of jeweled lighting. Comes from the term bling-bling.
The hood of the vehicle.
The trunk or liftgate of the vehicle.
Anything reflective added to a car to enhance appearance. May also be called chrome.


Short for cabin. The enclosed compartment of a vehicle which contains the driver and passengers.
Cab back
The cab of the vehicle is moved to the rear of the vehicle. Cars such as a 1970's Corvette could be considered cab back design.
Cab forward
The cab of the vehicle is pushed forward. This design aesthetic was popular with Chrysler in the 1990s with the introduction of their LH platform cars.
Character line
A line creased into the side of a car to give it visual interest. (interchangeable with swage line) Sometimes implemented by a rubbing strip.
Brightwork using chrome plating.
Material (usually plastic) added to exterior of the car which isn't structurally necessary. May be functional to keep out dirt/debris as in underbody cladding, or may be cosmetic.
Control Panel
Generally used in a Car/Truck for heating and cooling inside car environment according to the passenger requirements. Basically it is divided into Different modes, Blower speed functions, AC, Temperature, Fresh recirculation of air. World wide control panel manufacturers are BHTC, Delphi, Visteon, Valeo, etc.
The base of the windshield.


Daylight Opening (DLO)
US DOT Term: For openings on the side of the vehicle, other than a door opening, the locus of all points where a horizontal line, perpendicular to the vehicle longitudinal centerline, is tangent to the periphery of the opening.
US DOT Term: For openings on the front and rear of the vehicle, other than a door opening, daylight opening means the locus of all points where a horizontal line, parallel to the vehicle longitudinal centerline is tangent to the periphery of the opening.
Dead Cat Hole
The space between a car's tire and the wheel well. Currently there is a trend towards smaller dead cat holes.
The horizontal surface at the rear of the car, which usually serves as the trunk lid.
Dog leg
The area behind the rear door on a four-door car. This area is part of the quarter panel just behind the door and in front of the rear wheel house.
Down Road Graphic
The styling of the front end of the car, which people will instantly recognize and associate with a manufacturer. For example, the grille, lights and sometimes the DLO.
A convertible.


The body-skin panel at the front of the car.
Fender (wings, UK)
Term for cowl covering the wheels of the vehicles. In more modern automobiles, this refers generally to the body panel or panels starting at the front "bumper" to the first door line excluding the engine hood. The opposite of the fender is the "quarter panel".
A design used in older (pre-unibody) cars, trucks, and SUVs. The power train and body are mounted to a rigid structural framework called a rail.


A vent on the side of the fender that can be used as hot-air outlet, but usually decorative.
The glassed-in upper section of the car's body. Daylight Opening (DLO) in turn describes the actual window areas only.


a coupe or sedan lacking a center window post between the front windshield post and the rearmost window post or body section.
(1) The structural roof beam above the windshield. (2) The section of exhaust piping attached to the cylinder head.
Hofmeister kink
BMW's trademark reverse-sweep kick at the bottom of last roof pillar.
H-point (or HP (Hip Point)
the pivot point between the torso and upper leg portions of the body, either relative to the floor of the vehicle[1] or relative to the height above pavement level, as used in vehicle design.
Hood (Bonnet in English speaking countries outside North America with the exception of the Canadian Maritimes)
The engine cover on vehicles when the engine is located forward or aft of the passenger compartment.


Instrument Panel. The Dashboard is termed as Instrument Panel in Automotive Industries, sometimes this term is confused with the Instrument Cluster that is the group of speedometer, odometer and similar devices generally behind the steering wheel.


NACA duct
A distinctively shaped inlet that is flush and begins with a narrow, shallow inset and becomes progressively wider and deeper.


The distance which the car's body extends beyond the wheelbase at the front (front overhang) and rear (rear overhang). In car style design terms, this is the amount of body that is beyond the wheels or wheel arches.


An open vehicle, usually with 4 doors, with a removable and/or retractable cloth top and a windshield characterized by the lack of integrated glass side windows. Contemporary uses of this name do not always follow this original description or apply to an open vehicle.
A structural member that connects the roof to the body of the car. Pillars are usually notated from front to back alphabetically (e.g. A-pillar joins the windshield to the frontmost side windows, B-pillar is next to the front occupants' heads, etc.).
US DOT Term: Means any structure, excluding glazing and the vertical portion of door window frames, but including accompanying molding, attached components such as safety belt anchorages and coat hooks, that (1) supports either a roof or any other structure (such as a roll-bar) above the driver's head or (2) is located along a side edge of a window.
The area at the base of the windshield where the wipers are parked. Also refers to the main chamber in an intake manifold.
Ponton styling
a 1930s–1960s design genre when distinct running boards and fully articulated fenders became less common and bodywork began to enclose the full width and uninterrupted length of a car in a markedly bulbous, slab-sided fashion.
Plug-in hybrid electric vehicle
A hybrid vehicle that can be plugged into the electric grid to recharge its battery to reduce gasoline usage.[2]
All the components that generate power and deliver it to the tires.


(or rear quarter panel) refers to the panel at the back sides starting at the rear edge of the rearmost doors, bordered by at top by the trunk (boot) lid and at bottom by the rear wheel arches ending at the rear bumper. This is the opposite of the fender.
Literally, the term originally referred to the rear quarter or the car's length.


Rake is the angle between the vehicle and the horizontal axis of the ground. If the back is higher than the front, you have positive rake. If the front is higher than the back, you have negative rake. In early hot rod and custom cars, positive rake was created by varying tire size, and/or by suspension modification. In today's body design, positive rake is integral with some vehicles' styling, e.g. Mercedes E350 sedan.
An open vehicle, usually with 2 doors, with a removable and/or retractable cloth top and a windshield characterized by the lack of integrated glass side windows. Contemporary uses of this name do not always follow this original description.
The body section below the base of the door openings sometimes called the "rocker panels", or "sills".
Rocker Rail
Body armor protecting the Rocker, found mostly in off road vehicles. Term coined by engineers at MetalCloak.
Rubbing Strip
Plastic/rubber line or moulding to prevent side-swiping along the doors.


Inset or protusion that implies the intake of air. May be functional for cooling/ventilation or purely ornamental. Also Shaker scoop.
Scowling headlamps
Headlamps styled along a V-shape as viewed from the front, giving the impression of a scowl.
Once a vehicle designed to carry hunters and sportsmen; now a station wagon or vehicle combining features of a station wagon and a coupe.
Shoulder line
The line or "shoulder" formed by the meeting of top and side surfaces extending from hood/fender shoulder to boot-lid/quarter-panel shoulder. The strongest example of this feature can be found on more modern of Volvo Cars.
The body section below the base of the door openings sometimes called the "rocker panels", or "rockers".
Sill line
Imaginary line drawn following the bottom edge of the greenhouse glass.
Six line
A line extending from the C-pillar down and around the rear wheel well.
a convertible top which is made out of flexible materials like PVC or textile.
side covers for wheel arches, hiding the wheel - usually rear only. Also called Fender skirts.
A raised lip or wing which is used to 'spoil' unfavorable air movement across the body. Some designs are more functional than others.
Staggered wheel fitment
The front and rear wheels are different widths. On sporty rear wheel drive cars, the rear tires are usually wider than the front.
Crease in the sheet metal intended as a "speed line" styling feature. Exemplified in the doors of the Ferrari Testarossa.
Suicide door
rear-hinged type, opening from the front of the car. If accidentally opened while driving at a high speed, doors would be blown backward.
Swage line
Crease or curvature in the side of the body used to create visual distinction. Sometimes the crease is functional and improves rigidity of the outer body (interchangeable with character line).
Swedish Kiss
A negative flick out to a flat surface which frames trim sections or venting.


The distance across the car between the base of the left and right wheels. (Like wheelbase, but side to side.)
A typically large vehicle built using frame-on-rail construction consisting of a cab and a separate bed for cargo.
(Boot in UK) Compartment for storage of cargo which is separate from the cab.
Tube Fender
Replacement fenders found on off road vehicles designed as part of body armor for off road vehicles. Used to protect the thin sheet metal bodies from damage while off-roading.
Tumblehome (tumble home)
Generally refers to the way the sides of a car rounds inward toward the roof, specifically of the greenhouse above the beltline. This term is borrowed from nautical description of naval vessels.
Turn under
The shape of the rocker panel as it curves inward at the lower edge.


The mechanisms and parts which control the operation of the valves.


Shape of the car as seen in the side profile. May be positive, negative or neutral. If the front is lower than the rear, then it is wedge-positive. If the rear is lower it is wedge-negative. If the car appears level from front to rear, then it is wedge neutral.
Wheel arch
The visible opening in the side of a car allowing access to the wheel.
The distance front to back measured from where the front and rear wheels meet the ground.
Wheel well (or bucket)
The enclosure or space for the wheel.
Windshield Trim
US DOT Term: Molding of any material between the windshield glazing and the exterior roof surface, including material that covers a part of either the windshield glazing or exterior roof surface.
See Fender.

See also


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