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4MATIC is Mercedes-Benz's brand name for its all-wheel-drive system, which sends power to all four wheels for extra traction.
4ETS is Mercedes-Benz's brake-based traction system that brakes a spinning wheel to send drive to the wheels with grip, mimicking locking differentials.
6x4 denotes a six-wheeled vehicle, typically a truck, in which four of the six wheels are driven.
6x6 denotes a six-wheeled vehicle in which all six wheels are driven, for maximum traction off-road or under heavy loads.
The A-pillar is the structural roof support on each side of the windscreen, the frontmost of a car's roof pillars.
AC charging supplies alternating current to an EV, which the car's on-board charger then converts to DC to fill the battery.
ASR is a traction-control system that prevents the driven wheels spinning under acceleration by cutting power or braking the slipping wheel.
Active Body Control is Mercedes-Benz's active hydraulic suspension that actively counters body roll, dive and squat for a flat, controlled ride.
Active Cornering Enhancement is Land Rover's active anti-roll system that hydraulically reduces body lean in corners while keeping off-road wheel articulation.
Active noise cancellation uses microphones and speakers to generate anti-phase sound that cancels unwanted engine and road noise in the cabin.
Active roll mitigation reduces a vehicle's body lean in corners and counters rollover risk using active anti-roll or braking interventions.
ASSYST is Mercedes-Benz's flexible service-interval system that calculates when maintenance is due based on actual driving rather than fixed mileage.
Active suspension technology uses powered actuators to control each wheel's movement in real time, all but eliminating body roll, pitch and dive.
Active Tilt Control is an active anti-roll system that counters body lean in corners, and can even tilt the car into the bend like a motorcycle.
ATTS is a Honda front-axle system that actively shifts torque between the front wheels to improve cornering grip and reduce understeer.
AVCS is Subaru's variable valve timing system, which adjusts camshaft timing to improve power, efficiency and emissions.
Active Yaw Control is Mitsubishi's torque-vectoring system that varies torque between the rear wheels to sharpen cornering and reduce understeer.
Adaptive air suspension combines air springs with electronically controlled adaptive dampers, varying both ride height and firmness automatically.
Adaptive cruise control (ACC) maintains a set speed but automatically slows and accelerates to keep a safe gap to the car ahead.
Adaptive Damping System is Mercedes-Benz's name for its adaptive suspension, which varies damper firmness automatically for ride and handling.
Adaptive headlights swivel and adjust their beam in response to steering, speed and conditions to light the road better, especially around bends.
Adaptive suspension uses electronically controlled dampers that vary their firmness in real time to balance ride comfort and handling.
Adaptive transmission control is software that learns a driver's style and conditions to adjust how an automatic gearbox shifts.
ADAS is the umbrella term for the electronic systems that help the driver by warning of hazards, assisting control or intervening to prevent crashes.
AdBlue is a urea-based fluid injected into a diesel exhaust to convert harmful nitrogen oxides into harmless nitrogen and water.
An adjustable-height shoulder belt lets the upper seat-belt anchor be moved up or down so the belt sits correctly across the shoulder for different-sized occupants.
Advanced Compatibility Engineering (ACE) is Honda's body-structure design that spreads crash forces to better protect occupants and other vehicles.
Advanced restraint systems coordinate airbags, seat belts and sensors to protect occupants according to crash severity and occupant size.
Aerodynamics is the study of how air flows around a moving car, governing its drag, stability, downforce, wind noise and efficiency.
Air suspension replaces steel springs with air-filled bellows, allowing adjustable ride height and a consistently level, cushioned ride.
An airbag (SRS) is a fabric cushion that inflates in milliseconds during a crash to soften the occupant's impact against the car's interior.
The airbag control unit is the computer that reads crash sensors and decides when and how to deploy the airbags and seat-belt pretensioners.
Airmatic is Mercedes-Benz's air-suspension system, which combines air springs with adaptive damping for adjustable height and a refined ride.
All-wheel steering turns the rear wheels as well as the front, improving low-speed manoeuvrability and high-speed stability.
An all-season tyre is a compromise tyre designed to perform acceptably year-round, in dry, wet and light winter conditions, without seasonal swapping.
An ATV (all-terrain vehicle) is a small open vehicle with large low-pressure tyres, built to ride over rough ground off-road.
All-wheel drive (AWD) powers all four wheels, usually automatically, for better traction and stability in everyday and poor conditions.
Anti-skid control is a manufacturer name for a traction- and stability-control system that prevents wheel slip and skidding.
The anti-lock braking system (ABS) stops the wheels locking under hard braking, so the driver keeps steering control and stops in a shorter, controlled distance.
An anti-roll bar (sway bar) is a torsion spring linking the left and right wheels of an axle to reduce body lean in corners.
Approach angle is the steepest incline a vehicle can drive up to without its front bumper hitting the ground.
An attention control system detects signs of driver drowsiness or distraction and alerts the driver to take a break or refocus.
Audi Space Frame (ASF) is Audi's aluminium body construction that uses a frame of aluminium sections and castings to cut weight while keeping rigidity.
AMG is the high-performance division of Mercedes-Benz, named after its founders Aufrecht and Melcher and Aufrecht's birthplace, Großaspach.
An automatic braking differential uses the brakes to slow a spinning wheel, sending torque to the wheel with grip — a brake-based traction aid.
Automatic climate control maintains a set cabin temperature automatically, adjusting heating, cooling and fan speed without the driver intervening.
Automatic Distance Control is a radar-based system that keeps a set distance to the car ahead, automatically adjusting speed — a form of adaptive cruise control.
Automatic emergency braking (AEB) automatically applies the brakes when a collision is imminent and the driver hasn't reacted in time.
An automatic locking differential locks the two wheels on an axle together automatically when it detects slip, then unlocks for normal driving.
Automatic locking retractors let a seat belt be cinched tight and locked at a fixed length, mainly to secure a child seat firmly with the belt.
An automatic transmission changes gears by itself, without the driver operating a clutch, leaving them to use only the accelerator and brake.
An automobile is a self-propelled road vehicle, typically with four wheels, designed to carry a small number of passengers.
An axle is the shaft or assembly connecting a pair of wheels, supporting the vehicle's weight and, on driven axles, transmitting power to them.
Axle articulation is how far a vehicle's axles can flex and move to keep the wheels on the ground over uneven terrain.
Axle ratio is the gearing in the differential that sets how many times the driveshaft turns for each turn of the wheels.
Battery capacity is the total amount of energy an EV battery can store, measured in kilowatt-hours (kWh).
Battery degradation is the gradual, permanent loss of an EV battery's usable capacity and power over time and use.
A battery electric vehicle (BEV) is a car powered solely by a battery and electric motors, with no combustion engine at all.
Battery preconditioning warms (or cools) the EV battery to its ideal temperature before fast charging so it can accept full power.
Battery thermal management is the system that keeps an EV battery within its ideal temperature range during driving, charging and rest.
Belt force limiters let a seat belt yield slightly under extreme crash loads, reducing the force on the occupant's chest to prevent belt-induced injury.
Bi-xenon headlamps use a single high-intensity xenon gas-discharge bulb to provide both low and high beam, giving brighter, whiter light than halogen.
Bidirectional charging lets an EV both draw power from and send power back out, turning the car into a mobile battery.
Blind-spot monitoring warns the driver when another vehicle is in the hard-to-see area alongside and just behind the car.
Body roll is the sideways leaning of a car's body to the outside of a corner as it responds to cornering forces.
Body-side steps (running boards) are narrow platforms along the sills of tall vehicles to help occupants step up into the cabin.
Bottom-end power is the pulling strength an engine produces at low revs, giving strong, effortless acceleration without needing to rev hard.
Brake assist detects an emergency stop and applies maximum braking force, since many drivers don't press the pedal hard enough in a panic.
A brake caliper is the clamp that houses the brake pads and squeezes them against the brake disc to slow the wheel.
Brake fade is the temporary loss of braking power when the brakes overheat from heavy, repeated use.
Brake force display signals an emergency stop to following drivers, typically by flashing the brake lights or hazard lights to warn of hard braking.
Brake horsepower (bhp) is an engine's power measured at the crankshaft on a brake dynamometer, before transmission losses.
Brake lockup is when braking force overcomes a tyre's grip and the wheel stops rotating and skids, lengthening stops and losing steering control.
Brake pedal travel is how far the brake pedal moves before and during braking, a key part of brake feel and a clue to the system's condition.
Breakover angle is the steepest ridge a vehicle can drive over without grounding its belly between the wheels.
The C-pillar is the roof support behind the rear side windows, the third of a car's lettered roof pillars.
Cab-forward is a design that pushes the passenger cabin and windscreen forward over the front wheels to maximise interior space and improve proportions.
The camshaft is a rotating shaft with lobes that open the engine's valves at precisely timed moments in each cycle.
Carbon-ceramic brakes use discs made of carbon-fibre-reinforced ceramic for huge heat tolerance, low weight and long life on high-performance cars.
Cargo volume is the amount of luggage space a vehicle offers, measured in litres.
A catalytic converter is an exhaust device that uses precious-metal catalysts to convert toxic engine gases into less harmful ones.
CCS is the dominant European and North American DC fast-charging standard, combining AC and DC charging in one connector.
A center differential splits engine torque between the front and rear axles on all-wheel-drive cars while letting them rotate at different speeds.
The CHMSL is the third, high-mounted brake light — the central stop lamp above or in the rear window that supplements the two main brake lights.
The centre of gravity is the point where a vehicle's weight is balanced; a lower one improves handling and stability.
CHAdeMO is an early Japanese DC fast-charging standard, now largely superseded by CCS and NACS outside Japan.
The charging curve is the graph of how an EV's charging power changes as the battery fills during a fast-charge session.
Charging speed is how quickly an EV battery gains energy, expressed in kilowatts or in range (km/miles) added per unit of time.
The chassis is the structural framework of a vehicle that supports the body, engine, suspension and other components.
Child-security locks disable the interior door handles of the rear doors so a child cannot open them from inside while the car is moving.
A clutch is the device that connects and disconnects the engine from the transmission, allowing smooth starts and gear changes.
CO2 emissions measure the carbon dioxide a car emits per kilometre, in grams (g/km) — a direct proxy for fuel burned and climate impact.
A coil spring is a helical steel spring that supports the vehicle's weight and absorbs road bumps, the most common car suspension spring.
Common rail is a diesel fuel system that keeps fuel at very high pressure in a shared rail, ready to inject precisely into any cylinder on demand.
CRDi is Hyundai-Kia's brand name for a common-rail direct-injection turbodiesel engine.
CDI is Mercedes-Benz's brand name for its common-rail direct-injection turbodiesel engines.
A compact car is a mid-small class (the C-segment) larger than a supermini, offering family space with manageable size.
A composite cross-car beam is a lightweight structural member spanning the cabin behind the dashboard, supporting it and tying the body sides together.
Compression ratio is how much an engine squeezes the air-fuel mixture, comparing cylinder volume at the bottom of the stroke to the top.
CATS is Jaguar's adaptive damping system, which automatically varies the firmness of the dampers to balance ride comfort and handling.
The connecting rod links a piston to the crankshaft, converting the piston's up-and-down motion into rotation.
Control Trac is Ford's electronically controlled four-wheel-drive system that can run automatically or be locked into 4WD high or low range.
A convertible (cabriolet) is a car with a folding or retractable roof that can be lowered for open-top driving.
Cornering brake control adjusts the braking force between the wheels when braking in a bend to keep the car stable and prevent it spinning.
A coupé is a sporty, usually two-door car with a low, sloping roofline that prioritises style over rear-seat space.
The crankcase is the lower part of the engine that houses the crankshaft and forms the bottom structure of the engine block.
The crankshaft is the rotating shaft that gathers the pistons' power via the connecting rods and turns it into the engine's output rotation.
A crossmember is a structural beam running across the width of a vehicle's frame or body, tying the two sides together and adding rigidity.
A crossover is an SUV-styled vehicle built on a car platform, offering a high seating position with car-like comfort and efficiency.
A crumple zone is a structural area at the front and rear of a car designed to deform and absorb crash energy, protecting the rigid occupant cell.
Kerb weight is how much a car weighs ready to drive but with no passengers or cargo on board.
A CV (constant-velocity) joint transmits drive through a varying angle at a steady speed, letting driven wheels steer and move over bumps.
A CVT (continuously variable transmission) is an automatic gearbox with no fixed gears, giving a seamless, infinitely variable range of ratios.
Cyclist detection enables a car's sensors to recognise cyclists and trigger warnings or automatic braking to avoid hitting them.
Cylinder deactivation shuts off some of an engine's cylinders under light load to save fuel, reactivating them when more power is needed.
A damper is the suspension component that controls the motion of the springs, stopping the car from bouncing repeatedly after a bump.
Damping is the controlled resistance to suspension movement that stops the springs oscillating, provided by the dampers (shock absorbers).
Daytime running lights are lights that switch on automatically when the car is running, making it more visible to others during the day.
DC fast charging delivers high-power direct current straight to the battery, bypassing the car's on-board charger for rapid top-ups.
Departure angle is the steepest incline a vehicle can drive off without its rear bumper hitting the ground.
A diesel particulate filter (DPF) traps the soot particles in a diesel's exhaust, periodically burning them off to keep emissions clean.
A differential is the gear assembly that lets a driven axle's two wheels turn at different speeds while sharing engine power.
DSTC is Volvo's combined stability- and traction-control system that prevents skids and wheelspin to keep the car under control.
DSC is the brand name used by BMW and others for electronic stability control, which corrects skids to keep the car on the driver's intended path.
Direct injection sprays fuel straight into the combustion chamber at high pressure, rather than into the intake port, for finer control and efficiency.
Disc brakes slow a wheel by clamping brake pads against a spinning metal disc (rotor), the standard braking system on modern cars.
Distronic is Mercedes-Benz's adaptive cruise control, which maintains a set speed and a safe distance to the car ahead using radar.
DOHC (double overhead camshaft) is a valvetrain with two camshafts per cylinder head — one for intake valves, one for exhaust.
Double-wishbone suspension locates each wheel with two A-shaped arms, giving excellent control of wheel geometry for sharp handling.
A double-pod cockpit is a dashboard design with two rounded binnacles or "pods" housing the instruments, giving a driver-focused, twin-cowl look.
Downforce is the downward aerodynamic force that presses a car onto the road at speed, increasing tyre grip for faster cornering and braking.
The drag coefficient (Cd) is a number describing how easily a car's shape slips through the air.
A driver monitoring system uses an interior camera to watch the driver's eyes and head, checking they are alert and looking at the road.
A driveshaft is the rotating shaft that transmits torque from the gearbox to the differential, typically running the length of the car.
The drivetrain is the group of components that delivers power from the transmission to the wheels.
Drum brakes slow a wheel by pressing curved shoes outward against the inside of a spinning drum, an older design now mainly used on rear axles.
A dual-clutch transmission (DCT) is an automatic gearbox with two clutches that pre-selects gears for near-instant, seamless shifts.
Dynamic Brake Control is BMW's brake-assist system that applies maximum braking force in an emergency stop the driver hasn't braked hard enough for.
An e-CVT is a hybrid transmission that blends engine and electric-motor power through a planetary gearset, behaving like a continuously variable gearbox.
An electric motor converts electrical energy from the battery into rotational force to drive an EV's wheels.
Electric power steering (EPS) uses an electric motor, instead of a hydraulic pump, to assist the driver's steering effort.
An electric vehicle (EV) is any car that uses one or more electric motors for propulsion, in whole or in part.
Electronic air suspension is an air-spring system with electronic control of ride height and levelling, common on Land Rover and luxury models.
Electronic brakeforce distribution (EBD) automatically varies the braking force sent to each wheel for the shortest, most stable stop.
An electronic control module (ECM) is a computer that manages a vehicle system — most often the engine's fuelling, ignition and emissions.
An electronic control unit (ECU) is a computer that controls one or more of a vehicle's electrical systems — most commonly the engine.
Electronic differential lock (EDL) brakes a spinning driven wheel so torque is redirected to the wheel with grip, mimicking a limited-slip diff.
Electronic fuel injection (EFI) uses sensors and a computer to meter fuel precisely into an engine, replacing the mechanical carburettor.
Electronic stability control (ESC) detects when a car is starting to skid and brakes individual wheels to keep it on the driver's intended path.
An electronically controlled automatic is an automatic gearbox whose shifts are managed by a computer rather than purely hydraulically.
Emergency lane keeping actively steers or brakes to prevent the car leaving its lane into danger, such as oncoming traffic or a road edge.
Engine braking is the slowing effect produced by lifting off the throttle and letting the engine resist the wheels, instead of using the brakes.
Engine displacement is the total volume swept by all the pistons in one cycle, usually given in litres or cubic centimetres.
Euro 6 is the European Union emissions standard setting strict limits on the pollutants new cars may emit, in force since 2014–2015.
Euro NCAP is the European safety body that crash-tests new cars and awards a star rating from one to five for occupant and pedestrian protection.
EV efficiency is how much energy a car uses to cover a set distance, typically measured in kWh per 100 km or Wh per km.
An EV heat pump is an efficient heating system that moves ambient heat into the cabin instead of generating it with a resistive element.
EV range is the distance an electric car can travel on a full charge before the battery is depleted.
An executive car is a large, premium saloon (the E-segment) offering high comfort, refinement and technology for long-distance business travel.
Exhaust gas recirculation (EGR) routes some exhaust back into the engine's intake to lower combustion temperature and cut nitrogen-oxide emissions.
A fastback is a body style with a single, continuous slope from the roof down to the tail, for a sleek, aerodynamic profile.
The final drive ratio is the last gear reduction between the transmission and the wheels, set within the differential.
A fire prevention system reduces the risk of fire after a crash, typically by cutting the fuel supply and isolating the electrical system on impact.
Forward collision warning (FCW) alerts the driver when it detects a risk of crashing into the vehicle or obstacle ahead.
Four valves per cylinder is a common engine layout using two intake and two exhaust valves per cylinder to improve breathing.
Four-wheel drive (4WD or 4x4) powers all four wheels and, in its traditional form, adds low-range gearing and locks for serious off-road traction.
Four-wheel steering (4WS) steers the rear wheels as well as the front, tightening the turning circle at low speed and aiding stability at high speed.
Front-wheel drive (FWD) powers the front wheels, the most common and space-efficient layout for everyday cars.
Frontal area is the size of a car's front silhouette, which together with the drag coefficient sets total aerodynamic drag.
A fuel cell electric vehicle (FCEV) makes its own electricity on board from hydrogen, driving electric motors with only water as exhaust.
Fuel consumption is how much fuel a car uses to cover a given distance, the core measure of how economical it is to run.
Fuel cut-off is the engine management feature that stops injecting fuel when you lift off the throttle while in gear and moving.
Fuel injection is the system that sprays a precisely metered amount of fuel into an engine, replacing the carburettor on all modern cars.
Full-time 4WD permanently drives all four wheels and uses a center differential, so it can be used safely on any surface, including dry roads.
A gasoline particulate filter (GPF) traps the fine soot particles emitted by modern direct-injection petrol engines.
A gear ratio is the relationship between the rotation of two meshing gears, determining the trade-off between torque and speed in each gear.
A grand tourer (GT) is a high-performance coupé built for covering long distances at speed in comfort.
GAWR is the maximum weight a single axle of a vehicle is rated to carry.
GCWR is the maximum combined weight of a vehicle and its loaded trailer.
Gross vehicle weight (GVW) is the actual total weight of a vehicle including passengers, cargo and fuel.
GVWR is the maximum total weight a vehicle is certified to operate at, set by the manufacturer.
Ground clearance is the distance between the lowest point of a car's underside and the road.
A half-shaft is a shaft that transmits power from the differential to one driven wheel, one per side of a driven axle.
A hardtop is a rigid roof without a fixed central pillar, or a folding metal roof on a convertible.
A hatchback is a car with a rear door that opens upward, including the boot in the main cabin for flexible, easy loading.
Hauling capacity is the amount of cargo a vehicle can carry on board, closely related to its payload.
A head-up display (HUD) projects key driving information onto the windscreen so the driver can read it without looking away from the road.
A high centre of gravity means a vehicle's mass sits high up, increasing body roll and rollover risk.
The high-voltage battery is the large traction battery that stores the energy used to drive an electric vehicle.
HDi is the brand name used by Peugeot, Citroën and the PSA group for their common-rail direct-injection turbodiesel engines.
Hill holder briefly holds the brakes when starting on an incline, preventing the car rolling back while the driver moves from brake to accelerator.
Horsepower is the traditional unit of an engine's power — the rate at which it does work — and the most familiar measure of how strong an engine is.
Horsepower (hp) is the standard unit of an engine's power — the rate at which it does work — and a key measure of performance.
A hot hatch is a small hatchback fitted with a powerful engine and sporty chassis, combining everyday practicality with genuine performance.
A hybrid electric vehicle (HEV) pairs a combustion engine with an electric motor and small battery, with no plug — it charges itself as you drive.
Hydraulic valve adjusters use engine oil pressure to automatically keep valve clearances correct, eliminating manual valve adjustment.
A hypercar is the rarest, fastest and most expensive class of road car, beyond even the supercar in performance and price.
Independent suspension lets each wheel move up and down on its own, so a bump on one wheel doesn't disturb the others — improving ride and handling.
An induction motor is an electric motor that creates its rotor's magnetism by induction, using no permanent magnets or rare-earth metals.
An inline-6 is an engine with six cylinders arranged in a single straight row, prized for its inherent smoothness.
Insta-Trac is a General Motors four-wheel-drive system that lets the driver shift between two- and four-wheel drive on the move.
An integrated chassis control system coordinates a car's separate dynamics systems — braking, stability, steering, suspension — to work together.
Integrated child seats are booster or child seats built into a car's own rear seats, folding out when needed for older children.
Intelligent speed assistance (ISA) detects the prevailing speed limit and warns the driver — or gently limits the car — when it is exceeded.
An intercooler is a heat exchanger that cools the compressed air from a turbo or supercharger before it enters the engine.
An internal balancer (balance shaft) is a weighted, engine-driven shaft that counteracts an engine's inherent vibrations for smoother running.
An internal combustion engine (ICE) produces power by burning fuel inside its cylinders, driving pistons that turn the crankshaft.
The inverter converts the battery's direct current into the variable alternating current that controls an EV motor's speed and torque.
ISOFIX is the international standard for anchoring child seats directly to fixed points in the car, for a secure, error-free fit without the seat belt.
A kei car is a Japanese class of very small, light vehicle built to strict size and engine limits in exchange for tax and insurance breaks.
Kompressor is Mercedes-Benz's brand name for a supercharged engine — a belt-driven compressor that forces more air in for extra power.
A kilowatt (kW) is a unit of power — the rate of energy use or delivery — equal to 1,000 watts.
A kilowatt-hour (kWh) is a unit of energy — the amount used by a 1 kW load running for one hour — and the standard measure of EV battery size.
Litres per 100 km (L/100 km) is the standard European measure of fuel consumption — how many litres a car uses to travel 100 kilometres.
A ladder frame is a chassis made of two long rails joined by crossmembers like a ladder, onto which a separate body is bolted — strong and durable.
Lane centering assist actively steers to keep the car continuously in the middle of its lane, rather than only correcting at the edges.
Lane departure warning (LDW) alerts the driver when the car begins to drift out of its lane without indicating.
Lane keeping assist (LKA) gently steers the car back toward the centre of its lane if it begins to drift over a lane marking.
LATCH is the US standard for attaching child seats to dedicated anchors in the car, the American counterpart to ISOFIX.
A leaf spring is a curved strip (or stack of strips) of spring steel used to support heavy loads, traditional on trucks and load-carriers.
Level 0 is the SAE automation level in which the human driver performs all driving, even if warning and momentary-intervention systems are present.
Level 1 is the SAE automation level where a system continuously controls either steering or speed — but not both — while the driver does the rest.
Level 1 charging is the slowest EV charging, using a standard household socket to add only a few kilometres of range per hour.
Level 2 is the SAE automation level where the car can control both steering and speed at once, but the driver must supervise constantly and be ready to take over.
Level 2 charging is mid-speed AC charging from a dedicated wallbox or public AC point, the standard way most EV owners charge at home.
Level 3 is the SAE automation level where the car drives itself under defined conditions, letting the driver disengage — but they must take over when prompted.
Level 3 charging is the fastest category — high-power DC fast charging that adds long range in minutes for trips.
Level 4 is the SAE automation level where the car drives itself fully within a defined area or condition, with no need for a human to ever take over there.
Level 5 is the highest SAE automation level: the car can drive itself anywhere, in any condition a human could, with no steering wheel or driver needed.
An LFP battery is a lithium-ion battery using lithium iron phosphate cathodes — cheaper, more durable and cobalt-free, but slightly less energy-dense.
The lift coefficient measures how much upward (or downward) force a car's shape generates as air flows over it.
A liftback is a fastback-shaped car whose sloping rear opens as a large hatch, combining coupé looks with hatchback practicality.
A limited-slip differential (LSD) limits the speed difference between an axle's wheels, sending torque to the wheel with grip instead of letting one spin.
LINGUATRONIC is Mercedes-Benz's voice-control system, letting the driver operate phone, navigation and other functions by spoken command.
A liquid-cooled engine controls its temperature by circulating coolant through passages in the block and head to a radiator.
A lithium-ion battery is the rechargeable battery technology used in nearly all electric vehicles, storing energy by moving lithium ions between electrodes.
A live axle is a solid axle that drives a pair of wheels rigidly connected by a single beam, common on trucks and off-roaders.
Load floor height is how high the boot floor sits above the ground, affecting how easy it is to load heavy items.
A locking differential can lock an axle's two wheels together so they turn at the same speed, guaranteeing equal torque for maximum off-road traction.
A low emissions vehicle (LEV) is a car certified to emit fewer pollutants than a defined standard, often qualifying for incentives or low-emission zones.
Lugging is running an engine at too low an rpm for the load or gear, making it labour and shudder — potentially harmful over time.
An LUV (luxury utility vehicle) is a premium, high-specification SUV that pairs off-road or utility roots with luxury-car comfort and equipment.
A MacPherson strut is a compact, popular front-suspension design combining the damper and coil spring into a single load-bearing strut unit.
A manual stick shift is a manually operated gearbox, where the driver selects gears with a lever and a clutch pedal.
A manual transmission lets the driver select gears by hand, using a clutch pedal to disconnect the engine during each change.
Matrix LED headlights split the high beam into many individually controlled LED segments that dim around other road users while staying bright elsewhere.
A microcar is an extremely small, lightweight city vehicle, often classed as a quadricycle with limited power and speed.
A mild hybrid (MHEV) uses a small electric system, usually 48-volt, to assist the engine — but it cannot drive on electricity alone.
A minivan is a tall, box-shaped vehicle designed to carry up to seven or eight people with flexible, easy-access seating.
Motor Slip Regulation prevents the driven wheels locking from heavy engine braking on a slippery surface by briefly adding engine torque.
Miles per gallon (mpg) is the fuel-economy measure used in the UK and US, stating how far a car travels on one gallon of fuel.
MPGe (miles per gallon equivalent) is a US efficiency rating that expresses an EV's energy use in terms a petrol-car buyer can compare.
An MPV (multi-purpose vehicle) is a tall, flexible family car built to maximise interior space and seating, often with up to seven seats.
Multi-link suspension locates each wheel with several separate links, giving engineers fine control over ride and handling — common at the rear of better cars.
A multi-plate transfer is a clutch coupling that variably distributes torque between axles in on-demand all-wheel-drive systems.
NACS (SAE J3400) is the Tesla-originated North American charging connector that most automakers are now adopting in place of CCS.
A naturally aspirated engine draws in air using only atmospheric pressure, with no turbocharger or supercharger to force it in.
An NCAP safety rating is the star score a New Car Assessment Programme awards a car based on crash tests and safety technology, helping buyers compare safety.
NEDC (New European Driving Cycle) is the old European lab test for fuel economy and emissions, replaced by the more realistic WLTP.
Night vision uses an infrared or thermal camera to reveal pedestrians, animals and hazards beyond the reach of the headlights in the dark.
Nitrous oxide (N2O) is a gas injected into an engine to provide extra oxygen for combustion, giving a large, temporary boost in power.
An NMC battery is a lithium-ion battery with a nickel-manganese-cobalt cathode, offering high energy density for long range and strong performance.
NOx emissions are nitrogen oxides produced by high-temperature combustion, harmful air pollutants that cause smog and respiratory problems.
OPDS is a Honda system that senses an occupant's position and size to control airbag deployment, preventing harm to out-of-position or small occupants.
The on-board charger (OBC) is the unit inside an EV that converts AC mains power to DC to charge the battery, setting the car's maximum AC charging speed.
One-pedal driving lets you accelerate and brake with the accelerator alone, using strong regenerative braking to slow and stop the car when you lift off.
The operational design domain (ODD) is the specific set of conditions — roads, speeds, weather, area — under which an automated driving system is designed to work.
Overall height is the distance from the ground to the highest point of a vehicle.
Overall length is the total bumper-to-bumper length of a vehicle.
Overall width is the widest point of a vehicle's body, usually excluding the door mirrors.
Overdrive is a gear with a ratio below 1:1, letting the engine turn slower than the driveshaft for relaxed, economical cruising.
Parking assist helps the driver park, ranging from proximity sensors and cameras to systems that steer the car into a space automatically.
Part-time 4WD normally drives only two wheels and lets the driver engage four-wheel drive when needed, but only on loose, low-grip surfaces.
Payload capacity is the maximum weight of passengers and cargo a vehicle can legally carry.
Peak charging power is the highest rate, in kW, that an EV can draw while fast charging — a headline figure it holds only briefly.
Pedestrian detection enables a car's sensors to recognise people on or near the road and trigger warnings or automatic braking to avoid hitting them.
A permanent-magnet motor (PMSM) uses fixed magnets in its rotor for high efficiency and power density, the most common EV motor type.
A pickup truck is a vehicle with an enclosed cab and an open rear cargo bed, built for hauling and towing.
A piston is the cylindrical component that slides within an engine cylinder, driven down by combustion to produce power.
Plug & Charge lets an EV authenticate and pay for charging automatically just by plugging in, with no app, card or screen needed.
A plug-in hybrid (PHEV) pairs a combustion engine with a larger, grid-rechargeable battery that gives a useful electric-only driving range.
The power curve (powerband) is the way an engine's power and torque vary across its rev range, and the band of revs where it pulls best.
Power steering uses an external power source to reduce the effort the driver needs to turn the steering wheel.
Power Train Electronic Control is a control unit that manages the engine and transmission together for coordinated, efficient powertrain operation.
Power-to-weight ratio relates a car's power to its weight, a far better predictor of acceleration than power alone.
The powertrain is everything that generates and delivers a vehicle's power, from the engine or motor through to the driven wheels.
Push-button four-wheel drive lets the driver engage 4WD or switch ranges electronically with a button or dial, instead of a mechanical lever.
Pushrods are long rods that transmit motion from a camshaft low in the engine block up to the valves, in an overhead-valve (OHV) engine.
Rack-and-pinion is the standard car steering mechanism that converts the steering wheel's rotation into side-to-side movement of the wheels.
Range anxiety is the driver's worry that an EV will run out of charge before reaching a destination or charger.
A range extender (REx) is a small onboard generator — usually a compact petrol engine — that produces electricity to extend an electric car's range.
Real Driving Emissions (RDE) is an EU test that measures a car's pollutant emissions on real roads, not just in the laboratory.
Rear cross-traffic alert (RCTA) warns of vehicles approaching from the side when you are reversing out of a parking space or driveway.
Rear-wheel drive (RWD) powers the rear wheels, letting the front wheels focus on steering — favoured for performance and balance.
Rebound is the downward, extending movement of a car's suspension as a wheel returns from a bump or drops into a dip — the opposite of jounce.
A recovery strap is a strong, often elastic strap used to pull a stuck off-road vehicle free using another vehicle.
Regenerative braking recovers a vehicle's kinetic energy when slowing down, turning the motor into a generator to recharge the battery.
Road-sensing suspension continuously reads the road and wheel movements and adjusts the dampers in real time for the best ride and control.
A roadster is a two-seat open sports car focused on driving pleasure, with a simple folding roof.
A rocker arm is a pivoting lever that transfers the camshaft's motion to open an engine's valve.
Roll stability control detects the risk of a rollover and intervenes by braking wheels and cutting power to keep a tall vehicle upright.
Rolling resistance is the energy a tyre loses to deformation as it rolls, a force the vehicle must overcome that directly affects fuel economy and range.
A run-flat tyre is designed to keep working after a puncture, letting you drive on for a limited distance at reduced speed instead of stopping.
A seat-belt pretensioner instantly tightens the seat belt at the start of a crash to remove slack and hold the occupant firmly in place.
Seating capacity is the number of people a vehicle is designed and approved to carry, including the driver.
A sedan (saloon) is a three-box car with a separate, sealed boot behind the passenger cabin.
Selective catalytic reduction (SCR) is an exhaust after-treatment that uses AdBlue to convert diesel NOx into harmless nitrogen and water.
Semi-elliptic multi-leaf springs are the classic arched leaf-spring design, a stack of steel leaves forming half an ellipse, used on trucks and older cars.
Sequential turbocharging uses two turbos of different roles that come into play one after another to broaden boost across the rev range.
Shift-on-the-fly is the ability to switch between two- and four-wheel drive while the vehicle is moving, without stopping.
A shock absorber is the common name for the suspension damper that controls spring movement and stops the car bouncing after a bump.
"Shocks" is the everyday shorthand for shock absorbers — the suspension dampers that stop the car bouncing and keep the tyres on the road.
A shooting brake is a sporty estate, typically a coupé or two-door body extended with a long roof and rear tailgate.
Short-long arm (SLA) suspension is a double-wishbone design with a shorter upper arm than lower arm, optimising wheel geometry for grip.
A skid plate is a tough protective panel under a vehicle that shields vital components from damage when driving over rocks and rough terrain off-road.
SOHC (single overhead camshaft) is a valvetrain using one camshaft per cylinder head to operate both intake and exhaust valves.
A solid-state battery replaces the liquid electrolyte of a conventional lithium-ion cell with a solid one, promising more range, faster charging and greater safety.
Speed-rated tyres carry a code indicating the maximum sustained speed they are certified to handle safely under their rated load.
A start-stop system automatically switches the engine off when the car is stationary and restarts it instantly when you pull away, saving fuel.
State of charge (SOC) is how full an EV battery is at a given moment, expressed as a percentage of its usable capacity — the EV's fuel gauge.
State of health (SOH) measures how much of its original capacity and performance an EV battery retains as it ages, shown as a percentage.
An estate (station wagon) is a saloon-based car with an extended roof and a large rear tailgate for maximum boot space.
A strut is a structural suspension unit that combines a damper with a coil spring and helps locate the wheel, bearing some of the vehicle's load.
A subframe is a structural sub-assembly that carries the engine or suspension and bolts to the main body, isolating loads and vibration.
A supercar is an extremely fast, expensive and exotic sports car that sits at the top of mainstream performance.
A supercharger is a belt-driven compressor that forces extra air into an engine for more power, with no lag because it is driven directly by the engine.
A supermini is a small hatchback (the B-segment) balancing low cost and easy city use with enough space for everyday driving.
A surround-view camera combines feeds from several cameras into a single bird's-eye view of the car and its immediate surroundings.
Suspension is the system of springs, dampers and links connecting a car to its wheels, providing ride comfort, grip and control.
Suspension travel is the total distance a wheel can move up and down on its suspension, from full compression to full extension.
An SUV is a tall, roomy vehicle with a high driving position and the option of all-wheel drive, built for space and light off-road ability.
A swaybar is another name for the anti-roll bar — a torsion spring that links an axle's wheels to reduce the car's body lean in corners.
A tachometer is the gauge that shows engine speed in revolutions per minute (rpm), helping the driver judge gear changes and engine load.
TELEAID is an early Mercedes-Benz telematics system that automatically calls for help in a crash and provides emergency and roadside assistance.
Three-valve technology uses three valves per cylinder — typically two intake and one exhaust — as a middle ground between two- and four-valve designs.
A timing belt is a toothed rubber belt that synchronises the crankshaft and camshafts so the valves open in time with the pistons.
A timing chain is a metal chain that synchronises the crankshaft and camshafts, doing the same job as a timing belt but lasting far longer.
The tyre load index is a number on the tyre that indicates the maximum weight each tyre can safely carry when properly inflated.
A tyre pressure monitoring system (TPMS) warns the driver when a tyre's pressure drops significantly below the correct level.
The tyre speed rating is a letter on the tyre indicating the maximum speed it is certified to sustain safely at its rated load.
Tongue weight is the downward force a trailer's coupling places on the tow vehicle's hitch or tow ball.
Torque is the rotational, twisting force an engine produces — what you feel as a car's pulling power, especially from low speeds.
A torque-converter automatic is the traditional automatic gearbox, using a fluid coupling instead of a clutch to transmit power smoothly.
Torque vectoring actively varies how much drive each wheel receives to sharpen cornering and improve stability and traction.
A torsion bar is a steel bar used as a spring, resisting suspension movement by twisting along its length.
Torsion-beam (twist-beam) suspension is a simple, compact rear-suspension design that links the two rear wheels with a flexible cross-beam.
Towing capacity is the maximum weight a vehicle is rated to pull on a trailer.
Track is the distance between the left and right wheels on an axle — the same measurement as track width.
Track width is the distance between the centres of the left and right wheels on the same axle.
A traction control system (TCS) stops the driven wheels spinning when accelerating, by cutting power or braking the spinning wheel.
Traffic sign recognition (TSR) uses a camera to read road signs — especially speed limits — and display them to the driver.
A transfer case is the gearbox in a four-wheel-drive vehicle that splits power between the front and rear axles and often provides low-range gearing.
The transmission, or gearbox, is the component that uses a set of gears to adapt the engine's power to the right speed and torque for the wheels.
TDI is Volkswagen Group's brand name for its turbocharged direct-injection diesel engines.
A turbocharger uses the engine's exhaust gases to spin a compressor that forces extra air into the cylinders, boosting power and efficiency.
Turning circle is the diameter of the smallest circle a car can turn within, showing how manoeuvrable it is.
A twin-scroll turbo splits the exhaust flow into two separate channels feeding the turbine, reducing lag and improving response.
A twin-turbo engine uses two turbochargers to increase boost, reduce lag or improve breathing, depending on how they are arranged.
4x2 denotes a vehicle with four wheels of which two are driven — the two-wheel-drive configuration, often used for trucks and SUVs.
Two-wheel drive (2WD) is any layout where the engine powers only two of the vehicle's wheels — either the front or the rear pair.
The Type 2 connector is the standard European AC charging plug, also forming the top half of the CCS2 fast-charging socket.
Unified Chassis Control coordinates a vehicle's separate dynamic systems — braking, stability, steering — under one controller for better handling and safety.
Unitized construction (unibody) integrates the body and chassis into a single load-bearing structure, the standard for modern passenger cars.
A universal joint (U-joint) is a flexible coupling that transmits rotation between two shafts at an angle to each other.
Usable battery capacity is the portion of an EV battery's total energy that the car will actually let you use, after a protective buffer.
Valves are the precisely timed openings that let air-fuel mixture into an engine's cylinders and exhaust gases out.
A variable-geometry turbo (VGT) uses moveable vanes to adjust exhaust flow onto the turbine, giving strong boost across the whole rev range.
Variable valve timing (VVT) adjusts when an engine's valves open and close to optimise performance and efficiency across the rev range.
VDC is the brand name (used by Nissan, Subaru and others) for electronic stability control, which corrects skids to keep the car on its intended path.
VSC is Toyota's electronic stability control system, which detects and corrects skids by braking individual wheels and reducing engine power.
VSA is Honda's electronic stability control system, combining stability and traction control to keep the car on the driver's intended path.
Vehicle-to-grid (V2G) lets an EV feed electricity from its battery back into the power grid, typically at times of peak demand.
Vehicle-to-home (V2H) lets an EV power a house from its battery, acting as backup during outages or shifting cheap or solar energy to peak hours.
Vehicle-to-load (V2L) lets an EV power external devices directly from its battery through a standard socket, like a giant mobile power bank.
A ventilated disc is a brake disc with internal cooling vanes between two faces, shedding heat better than a solid disc to resist brake fade.
A viscous coupling is a fluid-filled device that transmits torque between two shafts when they rotate at different speeds, used in AWD and limited-slip diffs.
Vortec is a General Motors brand name for a family of petrol engines, originally denoting an intake design that promoted swirling, efficient combustion.
Weight-to-horsepower ratio is how much weight each unit of engine power has to move; lower is faster.
Wheelbase is the distance between the centres of a car's front and rear wheels.
A winch is a motor-driven drum and cable, usually mounted at the front of an off-road vehicle, used to pull itself or others free.
Window (curtain) airbags deploy down from the roof rail to shield occupants' heads along the side windows in a side impact or rollover.
A winter tyre is designed for cold, snowy and icy conditions, using a special rubber compound and tread that grip far better than summer tyres in winter.
WLTP is the current standardised lab test for fuel consumption, CO2 and electric range, designed to be far more realistic than the old NEDC.
xDrive is BMW's brand name for its all-wheel-drive system, which continuously varies the torque split between the front and rear axles.
Xenon HID is a headlight technology that creates light with an electric arc through xenon gas, far brighter and whiter than a halogen bulb.