Car Terminology Explained

Do you know your cabriolets from your coupes and your CV joints from your CVT? Car jargon can leave the best of us scratching our heads, wondering what on earth a particular word means. This is especially frustrating when you're trying to decipher your car’s latest repair bill or navigate a dealership.

Fear not: WhoCanFixMyCar is here to help you understand all the automotive terminology you need to speak fluent mechanic.

Contents:

A | B | C | D

E | F | G | H

J | K | L | M

N | O | P | Q

R | S | T | U

V | W | X | Y

Z

WhoCanFixMyCar’s Glossary of Car Terminology

A

ABS - Anti-lock braking system. Find out how it works here.

ACC - Adaptive cruise control, an adaptive system that manages and adjusts the speed of your car based on surrounding traffic.

Active suspension - A sophisticated, computer-controlled suspension system that uses powered actuators instead of shock absorbers and springs.

Aftermarket accessory - A piece of equipment purchased after, or separately from, the vehicle.

AFVs - Alternative fuel vehicles.

Anti-theft immobiliser - Prevents the car from starting when the key is not present.

A/T - Automatic transmission. A multi-speed transmission that doesn't require the driver to change gears manually.

AWD - All-wheel drive.

B

BHP - Brake horsepower, a unit of measurement to describe the power of a car's engine or electric motor generates.

Body roll - How much a car ‘leans’ to the side during cornering.

B-pillar - Two vertical struts in the middle of the car that support the roof.

Brake bias - The distribution of a car's braking power between the front and rear.

C

Cabriolet - a car with a roof that can be folded down.

Camber - The angle between the plane of a wheel's circumference and a vertical line, measured in minutes and degrees. The tops of a car's wheels tilt outwards when the camber is positive and inward when it is negative.

Carbon footprint - A measurement which considers a vehicle’s consumption of resources against the earth’s ability to regenerate those same resources.

Carburetor - Used primarily on older internal combustion engines, it is mounted on the intake manifold and supplies fuel.

Caster - The angle between a car's steering axis and a vertical line when viewed from the side, measured in degrees and minutes.

Catalytic converter - A component in the exhaust system containing a substance that reacts chemically with the engine’s fumes to produce less harmful gases. Find out more in this guide.

CAZ - Clean air zone. Learn about air pollution schemes here.

CC - Meaning ‘coupe convertible’. A coupe vehicle with a roof that folds down.

Centre differential - A differential used in four-wheel drive systems to distribute power to the front and rear differentials.

Chassis - A general term referring to the mechanical parts of a car attached to a structural frame.

City car - A small car, such as the Skoda Citigo (pictured below), which is designed for driving in small towns and cities.

Combustion chamber - The space in the cylinder when the piston is at the top of its travel.

Convertible - A car featuring a roof that can be folded down.

Coupe - Most have two doors and two seats and feature a low, sloping roof line. 

C-pillar - Two vertical struts that frame the rear window.

Crossover - an SUV based on a car platform.

Cruise control - When engaged by the driver, cruise control automatically controls the vehicle’s speed.

Crumple zone - Part of a vehicle that collapses upon impact to protect the passengers and driver.

Crossover - A car that is positioned somewhere between a sports utility vehicle and a family hatchback.

Cut and shut - A damaged car that has been repaired by fusing one or more vehicles together.

CVT - A transmission that has a continuously variable drive ratio (rather than having the usual gear ratios).

D

Depreciation - The proportion of a vehicle's initial purchase price that is lost over time.

Differential - A set of gears that transmits engine power to the wheels, allowing them to rotate at different speeds when turning.

Direct injection system - A fuel system whereby the injection nozzles are inside the combustion chamber.

Disc brakes - Also known as calliper disc brakes, this system consists of a disc that rotates at wheel speed and a calliper that can squeeze the surfaces of the disc around its perimeter.

Downforce - A vertical force directed downwards, created by the airflow around an object (such as a car body).

DPF - Diesel particulate filter. Learn more about it here.

D-pillar - Vertical or near-vertical struts on either side of the rear window, found in larger vehicles like SUVs.

Drivetrain - All of a car's components that produce power and transmit it to the wheels.

Drum brakes - A braking system that uses an iron casting shaped like a shallow drum that rotates with the wheel. Curved brake shoes are forced into contact with the drum to provide the braking force.

DSG - Direct shift gearbox. This is VW Group's dual-clutch gearbox that allows either automatic operation or semi-manual control using the floor-mounted selector and steering paddles.

E

ECU - Engine control unit. This is a car's onboard computer that regulates the engine by monitoring certain characteristics (i.e. coolant temperature and RPM) and controls variables (i.e. spark timing, EGR and the air-to-fuel ratio) using sensors.

EGR - Exhaust gas recirculation, a method of reducing NOx emissions by recirculating some of a car's exhaust gas into the inlet manifold. The gas absorbs heat during the combustion process and reduces the peak temperature during combustion.

EPS - Electric power steering, a system that makes it easier for the driver to turn the steering wheel.

ESC - Electronic stability control, a system that combats under and oversteer and increases safety by applying the brake to a particular wheel when it detects high slip angles.

Estate - A body style featuring a large and often boxy rear end which is designed to increase the boot space.

EV - Electric vehicle.

Ex-demo - Short for ex-demonstrator, this is a car that was once used for test drives by a dealership.

Exhaust manifold - A network of passages that gathers exhaust gases and sends them to the silencers and catalysts of the exhaust system.

Extended warranty - A vehicle warranty which extends the vehicle’s basic warranty beyond its original period. Find out how to keep your warranty valid.

F

Fastback - A car with two or four doors that has a sloping rear end. Mazda uses this term to refer to the Mazda3 hatchback.

Flywheel - A heavy disc attached to the crankshaft to smooth the engine's power flow. Learn more about flywheels here.

Fuel economy - The amount of fuel that a car uses over a certain distance. This guide explains how to get the best fuel efficiency out of a car.

Fuel injection - A system that provides fuel to an engine by measuring its needs and regulating the fuel flow through a pump and injectors.

G

Gross vehicle weight rating - Known also as GVWR. This is the sum of a vehicle’s curb weight, passenger weight capacity and cargo weight capacity. 

Ground effect - The phenomenon when the airflow between a moving object and the ground creates downforce.

GT - Grand Tourer, a car designed for long-distance driving.

H

Handling - A term used to describe a vehicle's behaviour related to its directional control. Handling is about how well your car corners and travels over different road surfaces.

Hatchback - This refers to a body style (pictured below) where the top of the boot door stretches the width of the rear-end of the car and has its hinges at the roofline, making it spacious. Here are the top ten cheapest hatchbacks to maintain.

HEV - Hybrid electric vehicle.

Hot hatch - A fast, sporty hatchback.

HPI check - A used vehicle history checking service that reports whether a vehicle has been stolen, written off or accident damaged.

Hybrid - A type of car that uses both regular fuel and a battery.

Hydrogen fuel cell - This is an alternative powertrain that produces electricity via electrochemical reactions. 

I

ICE - Internal combustion engine.

Immobiliser - An electric safety device that can be fitted to your car to stop the engine from turning on unless the correct key is used. They can also be mechanical, preventing the steering wheel from turning.

Independent suspension - A system that allows each wheel on the same axle to move independently.

Intake manifold - Distributes air to the engine's cylinders.

ISOFIX - The standard attachment for child safety seats that uses rigid connection points rather than a seatbelt.

J

Jacked-up - When the suspension of a vehicle has been changed to make it sit higher off the ground.

Jounce - The motion of a wheel that compresses its suspension.

Keyless ignition - A system that allows a car to start by the push of a button rather than using a key.

L

LED - Light emitting diode. A type of car bulb that is brighter, has a longer lifespan and is more efficient than a conventional bulb.

Limited slip differential - A differential that stops all the power being transmitted to just one wheel (for instance, if it's spinning on slippery ground).

Low emission zone - Sometimes referred to as an LEZ or clean air zone. Areas like this aim to reduce pollution levels.

M

Marque - A vehicle make or brand.

MHEV - Mild hybrid electric vehicle. This is a car that has an internal combustion engine but is also assisted by an electric generator.

Mid-engine - A vehicle composition that places the engine ahead of the rear axle but behind the front passenger compartment.

Modifications - Changes to a car that mean it is no longer in its original factory state.

MPG - Miles per gallon. The number of miles a car can travel per gallon of fuel it uses.

MPH - Miles per hour. How many miles a car can travel in an hour.

MPV - Multi-purpose vehicle, designed to provide plenty of interior space.

N

Naturally aspirated - When engine cylinders draw in the fuel mixture under atmospheric pressure by the suction action of the pistons, rather than it being forced by a supercharger or turbocharger.

NEDC - New European Drive Cycle. Used to assess emission levels and fuel economy of cars.

O

Octane - A flammable hydrocarbon found in petrol that reduces engine knock (when pockets of the air/fuel mixture detonate after the main combustion). High octane fuel is often recommended for high-performance sports cars.

Odometer - A device that record's a car's mileage.

OEM - Original equipment manufacturer.

Opposite lock - A technique to control an oversteering car that involves turning the steering wheel in the opposite direction to that which the car is turning.

Oversteer - When the rear wheels lose grip during cornering, creating the possibility of a tail-out slide.

P

PEV - Plug-in electric vehicle.

PHEV - Plug-in hybrid electric vehicle.

Platform - A manufacturing term for the base components of a car including its chassis, floor plan, suspension and steering system.

Power steering - Steering aided by hydraulic or electric motors.

Psi - pounds per square inch, a measurement of pressure.

Q

Q plate - A registration plate marked with a Q indicates the vehicle was either not originally registered in the UK, its age was unavailable at the time of its registration or it was built using many off-the-shelf parts (e.g. a kit car).

R

Range extender - Similar to a plug-in hybrid, but the engine is only used to recharge the batteries once they are flat.

Regenerative braking - Recharges the battery of a hybrid or electric vehicle by converting kinetic (movement) energy into electrical energy.

Roadster - A two door convertible (example pictured above).

RPM - Revolutions per minute of the engine.

RWD - Rear wheel drive.

S

Saloon - A body style where the door of the boot is usually hinged below the rear window.

Segment - Types of car are divided into groups based on their shape and size, e.g. city cars, superminis, executive cars, small family cars, sports cars, luxury cars and MPVs.

SORN - Statutory off-road notification, when you inform the DVLA you're no longer planning to use your vehicle on the roads.

Station wagon - Another name for an estate car.

Supercharger - Similar to a turbocharger, but the compressor is mechanically driven by the engine instead of driven by exhaust gases.

Supermini - Smaller than a regular family hatchback but larger than a city car.

SUV - Sports utility vehicle.

T

Torque - A measurement of an engine’s power relating to how forcefully it can rotate the crankshaft at a given speed.

Tourer - Another name for an estate car.

Traction control - A safety feature designed to prevent wheel spin by ensuring maximum traction between the tyres and road. Learn more about traction control.

Turbocharger - A device (pictured above) that uses an exhaust-driven turbine to force air into an internal combustion engine, increasing the engine’s power.

U

Understeer - When the front wheels slip during a corner and the vehicle doesn't turn to the degree requested by the steering wheel.

V

VIN - Vehicle identification number. A unique number assigned to a car during the manufacturing process.

Z

ZEV - Zero emissions vehicle.

Don't forget, whatever your car needs, WhoCanFixMyCar can help you find the right garage at the right price.

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