ABS - Anti-lock Braking System

ABS is a fundamentally important active safety device that helps to prevent the wheels from locking up during heavy braking, enabling the car to remain steerable and directionally stable in hazardous conditions e.g. on wet or slippery roads.

When braking, wheel speed sensors measure the road wheel speed and should one or more start to lock the system reduces brake pressure to the wheel/wheels. This regulating process makes itself known by pulses that the driver can feel through the brake pedal, which are accompanied by noises. This is done deliberately as a warning to the driver that a wheel or the wheels are at the limits of adhesion. So that the ABS can regulate effectively in this range the brake pedal must remain depressed - on no account should it be pumped. However an ABS system cannot be expected to shorten stopping distances under all conditions. When driving on gravel or on fresh snow covering a slippery surface, i.e. when the car should be driven slowly and carefully, the stopping distance may even be slightly longer.

Activated charcoal dust and pollen filter

The combined filter unit sandwiches a layer of activated charcoal granules between layers of wool fibres. The wool filters out dust and pollen particles, while the activated charcoal reduces odours and pollutants. The surface of the activated charcoal binds or changes the chemical composition of gaseous substances to make them safe. The majority of harmful low-level ozone, for example, is converted to harmless oxygen.

Adaptive airbags

The two front airbags, together with the seatbelt pretensioners, are stepped in their restraining effect. This means that the occupants are restrained in highly controlled manner. Potential injuries caused by the airbag are minimised.

Adaptive Cruise Control

A cruise control system with ADC allows for safe and comfortable driving - maintaining a driver-selected safety distance from vehicles ahead. A radar sensor constantly monitors the distance to the vehicles in front. When the distance is shorter than the one chosen, the ADC system slows the vehicle using the engine management and, if necessary, the brakes.

Active head restraints

Active head restraints offer improved protection against whiplash (trauma to the cervical vertebra) when the car is hit from behind. During this type of impact the occupant's body is pressed firmly into the seat which activates a mechanism that pushes the head restraint out and tilts it towards the back of the head in a fraction of a second. This reduction in distance between the head and the head restraint reduces forces acting on the neck by up to 60% and whiplash injuries by 30%.

Air suspension

Air suspension guarantees an extremely high level of comfort and, with speed-dependant automatic ride height lowering, sporty dynamics. Ride height adjustment can also improve handling and comfort on many systems, while certain 4x4s such as the Range Rover and Discovery 3 extra ground clearance when needed.

Anti-submarining seats

Anti-submarining seats incorporate a ramp in the seat base that prevents the occupant from slipping under the seatbelt in a collision

Automatic headlight levelling

Automatic headlight levelling devices ensure the headlights are always adjusted correctly irrespective of the loading condition of the car. Axle sensors measure the different spring compression at the rear axle and control the front headlights by a servomotor. Dynamic headlight levelling also registers the driving speed and compensates for quick changes in pitch and dive caused by the car braking or accelerating.

Brake Assist

Accident research has shown that the majority of drivers do not brake hard enough in emergency situations. This results in insufficient brake pressure being generated to achieve maximum vehicle deceleration, which lengthens the braking distance.

Brake Assist has been developed by several manufacturers to support the driver in critical braking situations. It detects how hard and how fast the driver applies the brakes in order to detect an emergency situation. In these situations Brake Assist applies maximum braking effort to reduce stopping distances by as much as 25%.

Collapsing pedal assembly

During a head-on collision there is a high risk of leg injury for the driver due to possible intrusion of the foot pedals. For this reason, the pedal assemblies on many modern cars are designed so that they are less likely to cause injury. During a head-on collision the crash energy operates a simple mechanical linkage that moves the pedal assembly away from the driver's feet.

Curtain airbags

Side airbags and curtain airbags are both triggered during a serious side collision - but only on the side of the impact. Curtain airbags protect the head and upper body of the front and rear seat passengers from intrusion and debris including glass. Curtain airbags usually extend from the A-pillar (the one at the windscreen) to the D-pillar on the driver's and front passenger's sides and inflate in one unit along the roof frame trim. Once activated, curtain airbags usually stay inflated for longer to offer the occupants protection in the event of a rollover after the collision.

Decoupling engine subframe

During a head-on collision a decoupling engine subframe helps to deflect impact energy away from the passenger safety cell under the car floor. A decoupling of the engine subframe from the chassis mounting points during a head-on collision ensures that deformation of the driver and passenger footwells is significantly reduced.

Direct petrol injection

Direct petrol injection technology developed by leading car manufacturers - for example PSA Peugeot Citroen and Volkswagen Group - is one of the biggest advances in petrol engine design since fuel injection replaced carburettors. Direct injection combines the kind of benefits that diesels are famous for, with the smoothness, performance, quiet running and responsiveness of the best petrol engines.

Conventional petrol injection mixes fuel with air in the inlet manifold, so the fuel-air mix always remains the same at any load. In contrast, direct petrol injection introduces a precisely metered jet of fuel directly into the combustion chamber. This gives exceptional performance at full throttle, exceptional efficiency at part load and low emissions at every engine speed.

Obtaining the required precision for direct petrol injection calls for high fuel pressure with a range of operating pressures from 40 to 110 bar so that the amount of fuel and timing of each injection can be precisely controlled. A specially designed intake manifold and specially-shaped piston crowns create ideal combustion conditions for all combustion modes.

Direct petrol injection engines that operate in lean-burn mode require a NOx-storing catalyst to collect, and temporarily store, the nitrogen oxides resulting from the lean-combustion operation of the engine.

Although most engines deliver their optimum lean-burn benefit with environmentally friendly sulphur-free fuels, they can make significant power and economy gains using the ultra-low sulphur high octane unleaded petrol (such as Shell Optimax) which is now commonplace throughout the UK.

ESP - Electronic Stability Programme

Now fitted to many cars as standard, or available as an option, ESP works in conjunction with ABS (see above) and has proved a major contributor to active safety. ESP monitors slip at the wheels and adjusts braking force and engine power accordingly. Thus, if a car starts to slip in a corner, ESP will apply braking force to the affected wheel, or reduce power, to enable the tyre to find grip again and prevent a skid.

Euro IV

The motor industry has made significant progress in improving engine technology and fuel quality. This has resulted in dramatic reductions in exhaust emissions. In 1992, exhaust emissions limits, known as Euro I, were introduced for new cars. More stringent limits were introduced in 1997/98 (Euro II) and a further tightening of maximum emissions was introduced in 2000 (Euro III). These developments have meant that the main vehicle emissions affecting local air quality have fallen by 45 per cent during the last decade. The motor industry introduced vehicles meeting Euro III standards a full year ahead of the legislated date. Furthermore, many new vehicles already meet Euro IV standards, which become mandatory on all cars from January 1, 2006.

Exhaust emissions are of particular interest to company car drivers who drive a diesel car. The system for calculating company car tax is based on a car`s carbon dioxide (CO2) emissions.

The normal minimum charge on 15% of the car `s price applies to cars that emit CO2 at or below 140g/km. The %age increases in 1 per cent steps for every additional 5g/km over the specified level - up to a maximum of 35%.

For diesel cars registered after January 1, 2006, the percentage based on the CO2 figure is increased by 3%. So if the percentage based on CO2 is 18%, the percentage used to calculate the tax charge will be 21%.

Euro NCAP crash tests

In co-operation with the European Commission, several European governments, consumer protection societies and automobile clubs have established themselves in Europe under the name of Euro NCAP (European New Car Assessment Programme).

Since October 1998 Euro NCAP is valid for all new model types of vehicles according to a new EU regulation. The test criteria consist of passenger safety in head-on and lateral collisions, safety of pedestrians and children on the backseats. The head-on collision (in which the vehicle crashes head-on or offset into rigid or yielding barriers) is simulated at a speed of 40 mph. In the lateral crash a mobile yielding barrier collides with the stationary test vehicle at a speed of 30 mph. The crash test performance is translated into an easy to compare star rating system with a maximum score of 5. It is worth noting that the results relate only to how a car performs in these specific crash conditions and should be taken as an indication of overall performance in a wide variety of real-life circumstances. Rear-end collisions are not carried out as part of the Euro NCAP crash test programme.

To see results for many popular models, visit www.euroncap.com.

GTI: Grand Touring Injection

The GTI badge was first seen on the original Volkswagen Golf, arguably the father of the 'hot-hatch' concept, which went on sale in the UK in 1977. Since then the GTI badge has been adopted by many manufacturers keen to describe the fast hatch derivatives in their model ranges.

'Infotainment'

Infotainment is the name given to audio/navigation systems that combine the functions of a radio/CD player with satellite navigation. In many cars, infotainment can also extend to include controls for other functions, such as air conditioning, on-board computer operation and auxiliary devices such as TV, DVD systems etc, where fitted.

Pedestrian protection

Protecting lives not only applies to the driver and passengers, but also to pedestrians and cyclists. That's why the front wings of many new cars incorporate specially designed crumple zones to reduce impact energy. Rounded body forms in areas where pedestrians or bicycle riders may impact the vehicle and the use of foam padding and flexible materials such as special plastics on the exterior of the body also reduce the likelihood of injury to third parties. Features such as increased distance between the engine block and bonnet are also a visible measure of pedestrian safety.

Power and torque

Power and torque figures are both measures of the engines output. Power, expressed in PS, kW or BHP, may be expressed as a measure of the power at the higher end of the engine's rev range which directly influences the vehicle's top speed and 0-62mph acceleration time.

Torque, expressed in Newton metres (Nm) or lb/ft, is another measure of an engine's output, experienced as engine flexibility or low-speed 'pulling power'. It can be demonstrated by a vehicle's in-gear acceleration performance - from, say, 50-70 mph in a high gear - and its towing capabilities. Torque is, in most cases, at its peak at low engine speeds: large capacity diesel truck engines, for example, display enormous torque characteristics at engine speeds of just 1,000-1,800rpm making them ideal for hauling heavy loads. By contrast, the engines in modern Formula 1 cars are tuned to deliver up to 1,000bhp at revolutions of up to 18,000rpm, though at the expense of low-speed torque: there is virtually no pulling power available at engine speeds of less than, say, 4,000rpm making flexibility virtually non-existent. But as F1 cars are designed to operate at or near peak revs, the lack of low-speed flexibility is less important than in a modern car.

Rain sensing wipers

Rain sensors activate the windscreen wipers automatically. An infrared LED (Light Emitting Diode) directs light at the interior surface of the windscreen at an angle, and any reflected light is then detected by a photo-sensor. As soon as water appears on the windscreen, less light is reflected from the surface - the signal received by the photo-sensor changes, causing the windscreen wipers to start operating.

The system always works with relative values; each time it is activated it samples the ambient and infrared light levels, ensuring that ice, dirt or cracks on the windscreen do not affect operation.

When interval wiping is activated, the windscreen wiper makes a so-called reference wipe. The sensor registers the strength of light after this one-off wipe. It then uses this as a reference value for a dry windscreen. If the amount of light penetrating then decreases, it interprets this as rain and starts the wipers.

Rollover protection

Many modern cabriolets offer active rollover protection where the rear head-restraints or a purpose installed roll-bar extend rapidly to create an occupant safety zone in conjunction with the windscreen A-pillars.

The airbag control unit is fitted with a yaw rate sensor that detects potential rollover incidents. The risk is evaluated, in combination with sensors within the control unit, and the rollover protection system is triggered. Spring tension releases the rollover protection within 0.25 of a second and locks it.

In most cases, rollover protection is activated in a rear collision, rollover or when an airbag has been triggered.

TDI: Turbo Direct Injection

TDI stands for Turbo Direct Injection - the term used to describe many of today's diesel engines. Various systems pressurise the diesel fuel as high as 30,000psi for optimum efficiency, a better fuel/air mixture for cleaner more efficient combustion and improved torque output. Variations, such as CDI (Mercedes-Benz), HDi (Peugeot/Citroen), CDTi (Vauxhall), TDCi (Ford) and CTD-i (Honda), use a common 'rail' where the fuel is held under pressure before injection, rather than unit injectors which are favoured by Volkswagen Group for Audi, SEAT, Skoda and Volkswagen diesel engines.

Cooling the air entering the engine from the turbocharger (intercooling) makes it more dense, which adds to the performance capability of a diesel engine, allowing a smooth supply of power even at low revolutions.

Torque converter

A torque converter contains hydraulic oil which transmits the power to an automatic gearbox. When starting from rest the converter slips as the fluid accelerates. This is noticeable because the engine speed is audibly faster than the actual acceleration. A direct connection between the gearbox and engine is made to improve fuel consumption and power delivery at higher speeds. This torque-converter lockup occurs in higher gears above approximately 45 mph.

Traction control

Traction control systems are, typically, incorporated within ESP (see above) and were previously fitted to higher output petrol and diesel engines before becoming more commonplace on less powerful models. The system detects slip at the wheels and applies the brakes momentarily or reduces power to curb unnecessary spinning. It can assist a smooth getaway and can prevent skids on slipper surfaces, particularly with rear-drive vehicles.

Traction control is useful, for example, when freeing a vehicle if it is stuck, when driving in deep snow or on a loose surface, or when driving with snow chains.

Variable turbine geometry

Fitted to the turbochargers of some higher-specification petrol and diesel models where high performance and greater flexibility is a priority. It combines the benefits of the low speed response of a small turbocharger and the high power output of a large turbocharger. In the lower engine speed range the velocity of the exhaust gas stream is not sufficient to accelerate the turbine to the required speed. This may be experienced in turbodiesel engines as the engine having very little power in the lower engine speed range. This can be counteracted by employing VTG which narrows the cross-section in the exhaust gas stream to spin the turbine faster in order to force air into the engine.

Winter pack

The Winter pack describes the options bundle which includes heated front seats and heated windscreen washer jets. Depending on the model additional specification may include headlight washers (Polo, Golf and Bora) foglights (Beetle) or a heated front windscreen instead of the heated windscreen washer jets(Sharan).

Xenon headlights

Bi-xenon headlights use gas discharge technology to produce a much clearer and brighter light to illuminates the road ahead more evenly. In the Gas Discharge Lamp (GDL) the electrical current does not flow through a filament but through a mixture of xenon gas and metallic halogens. Hence the term 'xenon headlights'.

The powerful light source requires 35 per cent less energy than conventional lights and thus helps to reduce energy consumption levels. The law requires that GDLs are specified with lens washers and automatic levelling function to prevent dazzle to other road users.

Advantages of xenon headlights: similar light colour to daylight approx. 20 times higher light output compared to 1-filament or 2-filament lamps better durability Main beam and dipped beam have similar light intensity and colour.