A glossary of automotive design terms

Cars and Design – my kind of stuff!

via Sajeev Mehta at hagerty.com

This series has always been about elevating discussions about car design for all, specifically in a space more public than most car design websites. Along the way I’ve used words that aren’t exactly common knowledge, and I’ve even made my own two-word phrase that encapsulates an otherwise complicated design disappointment.

I do my best to avoid car-design jargon, but that only goes so far. Clearly, the time has come to create a glossary of terms used here in the Vellum Venom column.

But this ain’t no rehash of what you see on Wikipedia, as these are the terms I’ve referenced in Vellum Venom on a somewhat regular basis. Many are germane to design students and scholars, but this glossary aims to be a more casual collection of words that come to mind when I walk around a vehicle. One final point: This is a living document that will be amended as feedback requires.

Feel free to ask for more terms in the comments section! (Last updated: 1/17/23) 

A

A-line: The line that creates the top half of a vehicle’s silhouette, regularly seen in “teaser” photos released by OEMs looking for a little promotion of a future product.

Axle: An imaginary line that starts from a wheel’s centerline and runs “through” the vehicle to the wheel on the opposite side.

A-pillar: When looking at a side view, the first roof pillar that helps frame the windshield. More info here.

Accommodation curve: When looking into an interior from the side, the arc in a seat’s back that ensures a comfortable distance between the chair and the pedals as the occupant moves the seat moves up or down.

Aerodynamics: The study of how air moves and influences a car’s performance, as a whole or at the component level.

Air dam: An aerodynamic panel added to the bottom of car’s front end to aid fuel economy and engine cooling.

Airfoil: The cross-sectional shape of a wing.

Aperture: An opening on a vehicle’s body. May be as small as a cooling duct or as big as the holes covered by doors/deck lid/hood.

Approach angle: The maximum angle a vehicle can climb without damaging the front bumper or front suspension.

Air curtains:Aerodynamic trick to reduce drag by directing air around the front wheels, often providing a marginal benefit to fuel economy.

Art and Science: Marketing term for Cadillac’s angular design language, first seen on the 2002 CTS sedan.

Art Deco: A style of visual arts originating in France in the early 1900s that influenced cars like the Talbot-Lago.

Asymmetry: A lack of a mirror image when examining the front or rear of a design from its centerline. See Land Rover Discovery.

B

Backlight: The back glass of a vehicle’s greenhouse.

Baroque: A 17th century art movement characterized by ornate and excessive ornamentation. Used to describe design elements of luxury cars from multiple time periods.

Belt line: A horizontal line that separates a vehicle’s lower body from the side windows (see greenhouse).

B-pillar: The second pillar of a roof, when moving backward from a vehicle’s nose, after the A-pillar.

Benchmarking: Line drawings of a concept placed over a vehicle chosen to be the concept’s template for size and proportion. 

Bevel: A hard-angled cut that adds slope to a component. See 1980s Lincoln Town Car.

Brand character: The visual building blocks of a design that signify a unique automotive brand. (See Hofmeister Kink.)

Bulkhead: A panel that separates a vehicle’s engine, passenger, and cargo compartments into distinct spaces.

Buttress: An angled panel that supports another design element, for visual or structural purposes (or both).

C

C-pillar: The third roof pillar, and the final one for conventional sedan and coupe body configurations. Learn more here.

Center High-Mount Stoplight (CHMSL): The third brake light set higher than those situated within the vehicle’s light assemblies at each corner at the rear.

Cab-backward design: Styling notion to push the passenger compartment (cab) further away from a front-mounted engine. Stronger cab-backward designs are regularly seen as more prestigious than weaker implementations.

Cab-forward design: The opposite of cab backward, affording more passenger space at the expense of engine access, and commonly associated with dedicated fleet vehicles (vans, cab-over trucks) and the Chrysler LH platform.

Cant rail: The portion of the roof that connects the A, B, C, and D pillars (when applicable) to each other.

Centerline: A line that runs through the center of something, used as an aid to create a symmetric design at the front or back of a vehicle.

Center of gravity: A point at which the majority of a vehicle’s weight is concentrated.

Chamfer: A bevel designed to connect two disparate surfaces.

Character line: A line stamped into a panel to add visual interest or improve structural rigidity (or both).

Clamshell: A portal (normally a hood) that opens in the same manner as a clam, thereby drastically altering the shape of a traditional fender. See Kia Soul.

Coach light: Ornamental light normally placed on the B- or C-pillars of a roof.

Contrast: A visual difference in the appearance of distinct elements in a design. Adding more or less contrast changes the impact of a design.

Cowl: The base of the windshield, and a flashpoint of significant cost and functionality for modern car design.

Cut line: Any break in the body used to separate unique features like doors, hoods, trunks, bumpers, and fascias.

D

DLO FAIL: A lament for the proliferation of opaque plastic panels in lieu of glass, visually cheating the shape of a vehicle’s greenhouse. More info here.

DNA: see brand character.

Daylight Opening (DLO): The glass area of a vehicle’s greenhouse as seen from the side. More info here.

Dash-to-axle [ratio]: The distance between the centerline of the front wheel and the bottom of the windshield. More info here.

Deck lid: The horizontal plane of a conventional trunk on a sedan or coupe.

Deflector: See fairing.

Departure angle: The maximum angle a vehicle can descend without damaging the rear bumper or exhaust.

Dogleg: The part of the quarter panel behind the rear doors of a four-door vehicle, its relationship to the door and the rear wheel arch makes it resemble a dog’s hind legs.

Dog’s eye view: Photography term used to show what a vehicle looks like from a low vantage point.

Down-the-road Graphic (DRG): Recognizable front-end styling, intended to help market/promote a vehicle’s brand via visual recognition. Ex. BMW’s kidney grilles.

Downforce: The weight of air (and gravity) that pushes down on the front or rear of a vehicle at speed.

Diffuser: An aerodynamic panel at the bottom rear of a vehicle, designed to draw air out of from underneath to increase downforce.

Drag: The force of air pushing against a vehicle at speed. NASA calculates this by taking the “drag coefficient times the density (of the air), times half of the velocity squared, times the reference area (frontal area).”

Drag coefficient: A unitless number calculated to determine the resistance of a vehicle at speed. More info here.

E

Eight-bit design: Retro design implementing pixels in a style befitting digital creations of the 1980s. See the Hyundai Ioniq 5.

F

Fairing: a part that is added to a vehicle (or a vehicle accessory, like roof racks) to reduce aerodynamic drag or deflect wind.

Facade: architectural term for the face of a building, but can be used to describe customer-facing elements of automobile design.

Fascia: the facade of either the front or rear of a vehicle.

Fast back: an elongated C-pillar that shortens the length of the deck lid relative to other body styles available for the same car. See the 1966 Ford Mustang.

Fender: when viewed from the side, the body panel that normally covers the space between the front bumper and the front door.

Firewall: see bulkhead.

Flying Buttress: an angled support beam, popularized by the back pillars of the 2001 Chevrolet Avalanche.

Frontal Area: the area inside the shadow that’s made when shining a light at the front of a vehicle.

G

Greenhouse: the upper part of a vehicle’s body that houses the glass, and resembles a greenhouse for growing plants indoors.

Globalization: in terms of car design, a business concept stressing interchangeability of platforms and parts across the globe. See the Chevrolet Spark ACTIV.

Ground Effects: functional extensions added to the rocker panels to generate downforce via low pressure between the chassis and the ground, often complemented with downforce added by front and rear wings.

H

H-point: the point of a seated human’s hip in car, when viewed at the side of an interior space.

Hard point: location on a body that cannot be changed as per the functional requirements of the vehicle.

Hatchback: a two-box design with rear access via a lift-up access door. See the Porsche 928.

Header panel: structural assembly mounted above the front bumper, housing the headlights, grille, and often a front fascia.

Heckblende: German word that explains filler panels visually connecting the left and right taillight to make a full-length taillight. Often aftermarket for vintage vehicles, but also see the Porsche Taycan.

Hockey stick: a unique curve to the quarter window (where it meets the base of the C-pillar) on Saab products.

Horizon line: the line that separates the earth from the sky.

Hofmeister Kink: a unique bend on a quarter window (where it meets the base of the C-pillar) on BMW products.

I

Impact structure: Crush space needed in a body for safety purposes, often related to front and rear overhangs seen in side view.

L

Laminar airflow: Streamlined flow whereby all air particles move at the same speed and direction.

Lift: The force acting to pull a vehicle off the ground at speed, either at the front or rear axle.

Liftback: see hatchback.

M

Marker light: An amber-colored light that does not flash and only exists for identification purposes.

Minimalism: A style of visual arts traced back to Japanese traditional notions, in which fewer elements make a design more valuable.

Modernism: A style of visual arts from the late 19th century that prioritizes the craftsmanship and style originating from changes found in the Industrial Age.

Molding: A protective or decorative trimming, most commonly seen as flexible strips placed along a vehicle’s sides.

N

NVH: Field of study aimed at reducing a vehicle’s Noise, Vibration, and Harshness characteristics, involving both engineers and designers.

Negative space: The area of a body that’s intentionally left empty. These can be functional (to improve aerodynamics, cooling) or ornamental (to reduce visual weight)

Neoclassic: Styling elements from the pre-WWI era but interpreted for contemporary times. See rococo and Zimmer Motor Cars.

O

Overhang: The part of the body that doesn’t reside within the wheelbase of the vehicle.

One-box design: When viewed from the side, a vehicle that incorporates passengers, cargo, and powertrain spaces within a single box. (Think of a city bus.)

Opera window: A decorative window added to the C-pillar. Primarily for rear seat occupant comfort, but can help reduce blind spots from larger C-pillars.

P

Parking light: See marker light.

Pillar: A vertical post that holds the roof above the body of a vehicle.

Pedestrian-friendly design: Originating from legislation in Europe that mandated a vehicle’s front end is shaped for pedestrian safety, and that hood height is tall enough to provide adequate space between a human body and the engine upon impact.

Perspective: The visualization of a 3-D form on a 2-D surface, with the assumption of a correct representation of all elements in the design.

Profile view: The side view of a vehicle.

Projector lens: A headlight assembly design that uses a focusing lens similar to that of the human eye.

Proportions: The interaction between individual styling elements either with the basic shape of a vehicle or amongst other elements in a smaller space. (Think headlight assemblies.) More info here.

Portholes: A round opening into which windows or cooling vents are implemented into the body.

Q

Quarter panel: When viewed from the side, the part of that body that fills the gap between the rear doors and the rear bumper.

Quarter window: Glass mounted at the trailing edge of the DLO, either in the C-pillar or in the rear door. Can be functional for cabin ventilation, or to aid in clearing window mechanisms in rear doors with irregular shapes.

R

Rake: The angle, measured from horizontal, of a design element when viewed from the side, most notably seen in windscreens and A and C pillars.

Reflector lens: Headlight design incorporating a complex reflector behind the light bulb to focus light into a beam.

Retro: A historical callback to vehicle design of the past, especially within the same brand as the vehicle in question.

Retrofuturism: A style of visual arts that depicts the future with elements of the past. Designer J. Mays applied this to the VW New Beetle, Audi TT, Ford Thunderbird, and others.

Rocker panel: The part of the body that’s below the doors.

Rococo: Art movement from the late Baroque period, often used as a pejorative for an overstyled element.

S

Sectional view: The shape of an object when a portion is cut out for easier visualization.

Shoulder line: A curve or bend along the body that provides visual separation on par with the way that broad shoulders separate an arm from the body. See 2000 Volvo S60 (below).

Signal light: A light that both flashes to indicate turning and softly illuminates like a marker light.

Surfacing: The act of contouring a flat piece of sheetmetal for visual or functional enhancement (or both). Popularized by Chris Bangle’s flame surfacing during his tenure at BMW.

Swage line: See character line.

Splitter: A front valance that extends farther forward than conventional air dams, pushing higher pressure air over the car to increase downforce at speed.

Spoiler: A barrier mounted on the rear deck with the purpose of directing air up and away from the car, reducing lift and preventing the turbulence that occurs when high and low pressure air interact behind the car. Not to be confused with a wing.

Streamline: The act of lowering the resistance of a design to aerodynamic drag by removing superfluous elements.

Streamline Moderne: A style of visual arts that “streamlined” Art Deco designs to make them more aerodynamic. See the Cord 810/812.

Symmetry: A mirror image of lines facing each other when comparing the left and the right side of an object relative to its centerline.

T

Texture: The look and feel of a surface, usually pertaining to unpainted trim on SUVs and off-road vehicles.

Tumblehome: A nautical design term applied to show the inward tapering of a greenhouse from the beltline to the top, when viewed from the front or rear of the vehicle.

Three-box design: When viewed from the side, a vehicle that houses passengers, cargo and the powertrain in individual boxes spaces within a single box. See the Ford Crown Victoria sedan.

Three-quarter view: Vantage point that’s halfway between the profile and the front (or rear) of the vehicle.

Two-box design: When viewed from the side, a vehicle that incorporates passengers and cargo in a singular box, with the powertrain in another box. See the Range Rover.

Turbulent airflow: Inconsistent speeds and directions in an airflow, the opposite of laminar airflow.

U

Underbody: Bottom of the vehicle, whose design is crucial to increasing aerodynamics, lowering NVH, and optimizing packaging guidelines.

Unibody: Chassis type that integrates both the structural frame and the body into a single, unitized, design.

V

Valance: Bumper extension that routes air like an air dam, but generally better integrated into a vehicle’s overall front end design.

Vanishing point: A point out in space where seemingly parallel or unrelated lines on a car would converge, if extended past the body.

Volumes: The basic shape of a vehicle, the outline of the body work when seen from the side. More info here.

Venturi Effect: An increase in speed when air is forced through a smaller space, with the result of lower air pressure for more downforce. See the rear section of the Ford GT.

Vent window: Moving glass panes attached to the front doors to aid in air circulation inside the cabin. Mostly seen on older cars, but the 2013 Ford Fusion had non-functional vent windows.

Visual weight: The force of an element within a vehicle that ultimately catches the viewer’s eye, thus altering the balance of a design. See the deck lid of the Continental Mark IV.

Vortex: Airflow pattern where the air rotates around its centerline.

Vortex generators: Small aerodynamic design feature that creates a vortex, when used in a series can reduce drag on a body panel or wing.

W

Wedge: When looking at the side view, the overall rake of the A-line from front to rear. Most vehicles have a taller rear, making a positive slope to the wedge.

Wedge design: Minimalist styling originating from Italian design studios of the 1970s, featuring literal wedge shapes. See the Lancia Stratos HF Zero.

Wheel well: The area housing a vehicle’s wheel, often lined with plastic, with or without enhancements like air curtains.

Wheelbase: Measurement of the space between the axles of a vehicle. More info here.

Wing: Often located significantly higher above the deck lid than a spoiler, it deflects air upward to increase downforce. See the McLaren Senna.