Automotive Technical Glossary

Active Differential Control: A relatively new technology is the electronically-controlled active differential. A computer uses inputs from multiple sensors, including yaw rate, steering angle, and lateral acceleration and adjusts the distribution of torque to compensate for undesirable handling behaviors like understeer. [read more]
Adaptative Cruise Control: Adaptative cruise control (ACC) is a cruise control system in some modern vehicles. The system also goes under the names of active cruise control (ACC) or intelligent cruise control (ICC). These systems use either a radar or laser setup to allow the vehicle to slow when approaching another vehicle and accelerate again to the preset speed when traffic allows.
Anti-lock Braking System: An anti-lock braking system (ABS) (translated from German, Anti-Blockier System) is a safety system on motor vehicles which prevents the wheels from locking while braking.
Brake Horsepower: The actual or useful horsepower of an engine, usually determined from the force exerted on a friction brake or dynamometer connected to the drive shaft.
Camshaft Profile Switching: Camshaft profile switching (CPS) is used in automobile engines to change the camshaft profile (the shape and size of the camshaft lobes) between one designed to be ideal for low-speed driving, and another which increases valve lift for higher performance.
Centimetre: A centimetre (symbol cm) is a unit of length in the metric system, equal to one hundredth of a metre.
Compact Graphite Iron: Compacted graphite iron, which is also known as CGI or Vermicular Graphite Iron, is a form of cast iron which has elongated graphite particles mixed with spherical graphite particles present within the alloy, as opposed to the graphite “flakes” present in typical cast iron. The shape of the graphite particles present in CGI greatly enhance the strength and hardness of the iron.
Computer Adaptive Technology Suspension: A sophisticated system that uses electronically controlled, two-stage, adaptive dampers whose characteristics are automatically adjusted within milliseconds in response to road conditions and driving inputs, for the optimum balance between ride comfort and control. Superceded in the 2010MY Jaguars by Adaptive Dynamics.
Computer-aided Design: Computer-aided design (CAD) is the use of computer technology to aid in the design and especially the drafting (technical drawing and engineering drawing) of a part or product. It is both a visual (or drawing) and symbol-based method of communication whose conventions are particular to a specific technical field. Drafting can be done in two dimensions (“2D”) and three dimensions (“3D”).
Cornering Brake Control: Cornering Brake Control (CBC) is a further development and expansion of ABS, designed to distribute braking force during braking whilst cornering. CBC interacts with ABS to counteract oversteer, and generates optimum distribution of braking effort in corners, keeping the vehicle heading in the intended direction, even if the brakes are applied suddenly.
Cubic Centimetre: A cubic centimetre (symbol cm³—the abbreviation cc, though widely used, is deprecated) is a commonly used unit of volume and corresponds to the volume of a cube measuring 1 cm × 1 cm × 1 cm. The symbol cc is still most commonly used in descriptions of the size of internal combustion engines where it describes the total volume of the piston displacement.
Decibel: The decibel (dB) is a logarithmic unit of measurement that expresses the magnitude of a physical quantity (usually power or intensity) relative to a specified or implied reference level. Since it expresses a ratio of two quantities with the same unit, it is a dimensionless unit. A decibel is one tenth of a bel (B). The decibel is commonly used in acoustics to quantify sound levels relative to some 0 dB reference. The reference level is typically set at the threshold of perception of an average human and there are common comparisons used to illustrate different levels of sound pressure.
Diamond-like Carbon: Diamond-like carbon (DLC) exists in seven different forms of amorphous carbon materials that display some of the unique properties of natural diamond. They are usually applied as coatings to other materials that could benefit from some of those properties. In the case of the third generation Jaguar V8 engines, for example, DLC has been used on the fuel pump tappets to reduce friction.
Diesel Particulate Filter: A diesel particulate filter (DPF), is a device designed to remove diesel particulate matter or soot from the exhaust gas of a diesel engine. Wall-flow diesel particulate filters usually remove 85% or more of the soot, and can at times (heavily loaded condition) attain soot removal efficiencies of close to 100%. A diesel-powered vehicle equipped with a functioning filter will emit no visible smoke from its exhaust pipe.
Dynamic Stability Control: See Electronic Stability Control
Electronic Brakeforce Distribution: Electronic brakeforce distribution (EBD) is an automobile brake technology that automatically varies the amount of force applied to each of a vehicle’s brakes, based on road conditions, speed, loading, etc. Always coupled with ABS, EBD can apply more or less braking pressure to each wheel in order to maximize stopping power whilst maintaining vehicular control.
Electronic Stability Control: Electronic stability control (ESC) is a computerized technology that improves the safety of a vehicle’s handling by detecting and preventing skids. When ESC detects loss of steering control, ESC automatically applies individual brakes to help “steer” the vehicle where the driver wants to go. Braking is automatically applied to individual wheels, such as the outer front wheel to counter oversteer, or the inner rear wheel to counter understeer. Some ESC systems also reduce engine power until control is regained.
Emergency Brake Assist: Emergency Brake Assist (EBA) is a safety system in vehicles designed to ensure maximum braking power is used in an Emergency stop situation. By interpreting the speed and pressure at which the brake pedal is pushed, the system detects if the driver is trying to execute an emergency stop, and if the brake pedal is not fully applied, the system overrides and fully applies the brakes until the Anti-lock braking system (ABS) takes over to stop the wheels locking up.
Engine Drag Torque Control: Engine-drag torque control prevents the driven wheels from locking due to the braking effect of the engine on slippery surfaces when the driver suddenly takes his foot off the accelerator or rapidly shifts down a gear. The braking effect of the engine may cause the driven wheels to skid. They temporarily lose traction and the vehicle becomes unstable. In such situations, engine-drag torque control maintains directional stability and boosts safety.
Exhaust Gas Recirculation: Exhaust gas recirculation (EGR) is a nitrogen oxide (NOx) emissions reduction technique used in most modern petrol and diesel engines. EGR works by recirculating a portion of an engine’s exhaust gas back to the engine cylinders. Intermixing the incoming air with recirculated exhaust gas dilutes the mix with inert gas, lowering the adiabatic flame temperature and (in diesel engines) reducing the amount of excess oxygen. The exhaust gas also increases the specific heat capacity of the mix, lowering the peak combustion temperature. Because NOx formation progresses much faster at high temperatures, EGR serves to limit the generation of NOx. NOx is primarily formed when a mix of nitrogen and oxygen is subjected to high temperatures.
Horsepower: A unit that is used to measure the power of engines and motors. One unit of horsepower is equal to the power needed to lift 550 pounds one foot in one second. This unit has been widely replaced by the watt in scientific usage; one horsepower is equal to 745.7 watts.
Hundred weight: Hundred weight (or hundredweight) is a unit of measurement for mass historically used in the Imperial system, in which a hundredweight (‘long’) is defined as 112 avoirdupois pounds, or 8 stone, or four quarters (50.80234544 kg). The hundredweight is abbreviated cwt, where wt is an abbreviation for weight and c is an abbreviation for one hundred (since the Roman numeral C is equal to 100).
Kilometres per Hour: The kilometre per hour is a unit of both speed and velocity. The unit symbol is km/h or km·h⁻¹; however, the colloquial abbreviations “kph” and “kmph” are sometimes also used in English-speaking countries, in analogy to mph, although these are not in accordance with international scientific standards.
Litre: The litre is a unit of volume. The international unit of volume is the cubic metre (m³). One litre is equal to 0.001 cubic metre and is denoted as 1 cubic decimetre (dm³).
Miles per Hour: The mile per hour is a unit of speed, expressing the number of international miles covered per hour. A common abbreviation is mph or MPH, although mi/h is sometimes used in technical publications.
Millimetre: A millimetre (symbol mm) is a unit of length in the metric system, equal to one thousandth of a metre.
Monocoque: Monocoque (French for “single” (mono) and “shell” (coque)) is a construction technique that supports structural load using an object’s external skin. This stands in contrast with using an internal framework (or truss) that is then covered with a non-load-bearing skin. Monocoque construction for cars became popular after the war.
Motor Industry Research Association: The Motor Industry Research Association, often known as MIRA, is a limited company based near Nuneaton in Warwickshire in the United Kingdom, which provides product engineering, research, testing, information and certification services to the automotive sector. It was formed in 1946.
MP3: The term “MP3” refers to compressed digital audio data. The MP3 format is a widely used standard for compressing digital audio data. Compared to an audio CD of virtually the same sound quality, MP3 files only occupy one-tenth of the memory space. “MP3” stands for MPEG 1 Audio Layer 3. MPEG is a process for compressing digital video and audio data and is developed by the “Motion Picture Experts Group”.
Newton Metre: Newton metre is the unit of moment (torque) in the SI system. The symbolic form is N m or N·m, and sometimes hyphenated newton-metre. It is a compound unit of torque corresponding to the torque from a force of one newton applied over a distance arm of one metre.
Nitrogen Oxide: NOx is a generic term for mono-nitrogen oxides (NO and NO₂). These oxides are produced during combustion, especially combustion at high temperatures. At ambient temperatures, the oxygen and nitrogen gases in air will not react with each other. In an internal combustion engine, combustion of a mixture of air and fuel produces combustion temperatures high enough to drive endothermic reactions between atmospheric nitrogen and oxygen in the flame, yielding various oxides of nitrogen.
Noise, Vibration, Harshness: Noise, vibration, and harshness (NVH), also known as noise and vibration (N&V), is the study and modification of the noise and vibration characteristics of vehicles, particularly cars and trucks. Interior NVH deals with noise and vibration experienced by the occupants of the cabin, while exterior NVH is largely concerned with the noise radiated by the vehicle, and includes drive-by noise testing.
Pound (force): The pound or pound-force (abbreviation: lb, lbf) is a unit of force. The pound-force is approximately equal to the gravitational force exerted on a mass of one avoirdupois pound on the surface of Earth.
Pound (mass): The pound or pound-mass (abbreviation: lb, lbm) is a unit of mass used in the imperial system. A number of different definitions have been used, the most common today being the international avoirdupois pound of exactly 0.45359237 kilogram.
Revolutions per Minute: Revolutions per minute (abbreviated rpm, RPM, r/min, or r·min−1) is a unit of frequency: the number of full rotations completed in one minute around a fixed axis. It is most commonly used as a measure of rotational speed or angular velocity of some mechanical component, in automtive terms it often refers to the speed of the engine.
Straight-4 Engine: The straight-4 or inline-4 engine is a four cylinder internal combustion engine with all four cylinders mounted in a straight line along the crankcase. The single bank of cylinders may be oriented in either a vertical or an inclined plane with all the pistons driving a common crankshaft. Where it is inclined, it is sometimes called a slant-4. The straight-4 layout confers a degree of mechanical simplicity which makes it popular for economy cars.
Straight-6 Engine: The straight-6 or inline-6 engine is a six cylinder engine with all six cylinders mounted in a straight line along the crankcase. The single bank of cylinders may be oriented in either a vertical or an inclined plane with all the pistons driving a common crankshaft. Where it is inclined, it is sometimes called a slant-6. The straight-6 layout is the simplest engine layout that possesses both primary and secondary mechanical engine balance, resulting in relatively low manufacturing cost combined with much less vibration than engines with fewer cylinders.
SU Carburettors: SU carburettors (named after Skinners Union, the company that produced them) were a brand of carburettor usually of the sidedraught type but downdraught variants were used on some pre-war cars. The beauty of the SU lies in its simplicity and lack of multiple jets and ease of adjustment.
Torque: A torque, also called a moment, is a vector that measures the tendency of a force to rotate an object about some axis (centre). The magnitude of a torque is defined as the product of a force and the length of the lever arm (radius). Just as a force is a push or a pull, a torque can be thought of as a twist. The SI unit for torque is the newton meter (N m). In Imperial units, it is measured in foot pounds (ft·lb).
Traction Control System: A traction control system (TCS), also known as Anti-Slip Regulation (ASR), on current production vehicles, are typically (but not necessarily) electro-hydraulic systems, designed to prevent loss of traction of the driven road wheels, and therefore the control of the vehicle, when excessive throttle is applied by the driver, and the condition of the road surface (due to varying factors) is unable to cope with the torque applied. Although similar to electronic stability control (ESC) systems, traction control systems do not have the same goal.
Trailing Link Suspension: A suspension link that is aligned to resist longitudinal motions in a wheel; it is mounted to the chassis ahead of the wheel.
V12 Engine: A V12 engine is a V engine with 12 cylinders mounted on the crankcase in two banks of six cylinders, with all 12 pistons driving a common crankshaft. Since each cylinder bank is essentially a straight-6, this configuration has perfect primary and secondary balance no matter which V angle is used and therefore needs no balance shafts. A V12 with two banks of six cylinders angled at 60°, 120°, or 180° from each other has even firing with power pulses delivered twice as often per revolution as, and is smoother than a straight-6 because there is always even positive net torque output with little variation.
V6 Engine: A V6 engine is a V engine with 6 cylinders mounted on the crankcase in two banks of three cylinders, with all 6 pistons driving a common crankshaft. The V6 is one of the most compact engine configurations, shorter than the straight 4 and in many designs narrower than the V8 engine, and is well suited to the popular transverse engine front-wheel drive layout. It is becoming more common as the space allowed for engines in modern cars is reduced at the same time as power requirements increase, and has largely replaced the inline-6, which is too long to fit in many modern engine compartments. Although it is more complicated and not as smooth as the inline 6, the V6 is more compact, more rigid, and less prone to torsional vibrations in the crankshaft.
V8 Engine: A V8 engine is a V engine with 8 cylinders mounted on the crankcase in two banks of four cylinders, with all 8 pistons driving a common crankshaft. In its simplest form, it is basically two straight-4 engines sharing a common crankshaft. However, this simple configuration, with a single-plane crankshaft, has the same secondary dynamic imbalance problems as two straight-4s, resulting in annoying vibrations in large engine displacements. As a result, since the 1920s most V8s have used the somewhat more complex crossplane crankshaft with heavy counterweights to eliminate the vibrations. This results in an engine which is smoother than a V6, while being considerably less expensive than a V12 engine.
Variable Camshaft Timing: Variable camshaft timing (VCT) is used to vary the valve timing in automobile engines in order to minimise emissions and maximise power and torque over a wider range of engine speeds. Traditionally, the actuators used oil pressure, but the most recent Jaguar engines now utilise the positive and negative torques generated by opening and closing the intake and exhaust valves.
Variable Inlet Manifold: Variable inlet manifold (VIM) or variable length inlet manifold (VLIM) is used to vary the length of the intake tract in automobile engines in order to optimise power and torque, as well as provide better fuel efficiency.
ZF Friedrichshafen AG: ZF Friedrichshafen AG (often abbreviated to ZF) is a leading worldwide supplier of driveline and chassis technology. ZF products include automatic and manual transmissions for cars, trucks, buses and construction equipment.

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Automotive Technical Glossary