On gravel roads the braking distance might be increased by ABS, however the system lets the driver steer the car. A few cars give the driver the option of switching off the ABS if they think they can outperform it in some circumstances. If driving one of these, be sure you know the current status of the systems.

AIRBAG (SRS)
Safety belts must still be used even when airbags are fitted. Airbags are intended to supplement safety belts, not to replace them. Which is why they are technically called Supplementary Restraint Systems, or SRS.

Airbags explode from the centre of the steering wheel and sometimes also from the dashboard ahead of the front passenger when a crash starts to occur.

Some cars now have side airbags which come out of the front door trim or the sides of the seats themselves. A few even have air curtains that fall down from the tops of the doors, offering side protection to either the front seat occupants or to all occupants. Airbags cushion some of the shock of the crash and reduce the chances of them hitting unyielding parts of the car's interior.

The airbag remains inflated only very briefly. Apart from hearing a very loud bang, the car's occupants may not be immediately aware that it has been activated until they see the collapsed bag.

ALL-WHEEL DRIVE
(See Four-wheel drive)

CENTRAL LOCKING, POWER LOCKING
All the doors are locked and unlocked at the same time, either by a turn of a key or a remote control pad. In cheaper systems, only the driver's door lock operated all the others while more expensive systems have the central locking operating on both front doors, or even from the boot lock as well.

An increasingly common feature is two-stage central locking. Turn the key to the first position and only the driver's door is unlocked. Turn it further and central locking operates on all the other locks. This prevents an unwanted intruder from opening a passenger door.

At the summit of the central locking tree is the remote control unit. Push a button at a distance of several metres and the car is locked or unlocked, possibly with the car alarm being switched on/off at the same time.

CLIMATE CONTROL
This is an advanced type of air conditioning where you set the desired temperature and the climate control system maintains it, and the humidity level, automatically. Usually only fitted to upmarket cars, it's sometimes an extra-cost option on lower-priced vehicles.

Some climate-control systems offer the option of setting some items yourself. Other systems insist on making all the decisions for you. The drawback of the latter is that it frequently turns the interior fan onto full for several minutes when the car is hot after sitting in the sun and this can be distracting while driving.

Some car makers misleadingly call basic air conditioning 'climate control' so check which you are buying.

CRUISE CONTROL
Cruise control keeps the car at a predetermined speed without the driver's foot on the accelerator. It should not be confused with a hand throttle, fitted to some 4WDs.

Cruise helps you avoid getting booked for speeding when you inadvertently creep up to an efficient speed instead of holding back to a speed limit too slow for the conditions.

The car may lose speed when going up a steep hill, and it may pick up speed on a steep downslope where engine braking isn't sufficient to keep the speed down. Keep a close eye on the speedometer under these conditions.

Most cruise controls let you increase and decrease the car's speed manually with the hand controls.

When using cruise control, always keep your foot in the vicinity of the brake pedal in case of emergencies. All cruise controls are disconnected automatically if you touch the brake pedal and, on a manual car, the clutch pedal.

CV (CONSTANT VELOCITY) JOINTS
CV joints are used at the front wheels of front-wheel-drive cars to transfer engine power to the wheels, even while they are turned to steer the car.

They are virtually troublefree in modern front-drive cars but can cause real hassles in some older ones. They can be repaired at moderate cost in most cars.

DIESEL ENGINES
Diesel engines are more economical on fuel than petrol engines and generally last longer between major overhauls.

On the downside, they are more expensive to buy, give less performance and are noisier than petrol engines. Diesel fuel is oily to the touch and it doesn't seem to matter how careful you are during refuelling, you still end up with some on your hands.

Some of the latest-generation diesel cars are only a little noisier than their petrol-engined siblings.

Most major service stations sell diesel fuel, especially in the bush, but it is seldom discounted like petrol.

DOUBLE OVERHEAD CAMSHAFT
(DOHC) See Twin Cam

ELECTRONIC FUEL INJECTIONS (EFI)
Electronic fuel injection is more efficient than a carburettor in controlling the flow of fuel into the engine. More power and lower fuel consumption is the result.

Less maintenance is needed on an EFI system than on a carburettor, but an overhaul is more expensive. However, many last for the lifetime of the engine.

The simplest EFI system is single-point, sometimes called throttle-body. It uses a single fuel injector. It is a low-cost system which lies about midway in efficiency between a carburettor and a full fuel-injection system.

Much more common is multi-point fuel injection, which has an injector at each cylinder. Multi-point injection can be sub-classified into three types. In increasing order of efficiency, these are non-sequential, semi-sequential and sequential.

Once only seen on expensive upmarket cars, EFI is used these days on all but a few of the cheapest new cars. Some older cars have a mechanical fuel-injection system, or a hybrid mechanical-electronic one, but these can be troublesome as they get old.

FOUR-WHEEL DRIVE (4WD)
A car has greater grip on the road if driven by all four of its wheels. This means safer motoring in slippery conditions such as in wet weather or on dirt roads. It is particularly useful in icy or snowy conditions.

Four-wheel-drive cars aren't intended to be taken off-road like conventional truck-like 4WDs. Indeed, in an attempt to differentiate 4WD cars from 4WD trucks, some makers are trying to rename them all-wheel drive (AWD).

Extra weight and friction due to the additional components reduce performance and increases fuel consumption. Four-wheel-drive cars are more expensive than two-wheel drive, everything else being equal.

FRONT-WHEEL DRIVE
The front wheels (not the rear) are driven by the engine. The engine is normally mounted transversely across the car's body in a front-wheel-drive car, though in some cars it's mounted fore and aft.

All things being equal, there will be more passenger space in the cabin and a roomier boot because the engine is kept well forward in the body.

There are no space-robbing components to take the power back to the rear wheels and no differential under the boot.

Most big cars still have rear-wheel drive, which gives a car better towing abilities. Because of the car's larger overall size, rear-wheel drive causes fewer interior space disadvantages in big cars than it does in smaller ones.

The vast majority of small and mid-size cars built since the early 1980s use a transverse engine/front-wheel-drive layout.

HANDLING AND ROADHOLDING
Roadholding means the ability of the car to grip the road. Handling means the car's behaviour when it's being driven, not only how it steers but also how it reacts to irregularities in the road surface and even to the way it reacts to crosswinds or headwinds.

On a dry road in a modern car, you have to get going very hard to experience loss of tyre grip and anything other than neutral handling or mild understeer. So don't become overly concerned about road testers' comments on handling in extreme conditions unless you intend to drive the car fast and hard.

On the other hand, you should certainly have the driving ability to get the car out of trouble should you encounter any problems. An advanced driving school can help.

See also
UNDERSTEER AND OVERSTEER

INDEPENDENT REAR SUSPENSION (IRS)
As the name suggests, the car's rear wheels are free to move up and down independently of each other. This means the car is less disturbed by uneven road surfaces, particularly on rough bush roads, allowing a better ride and more precise roadholding.

LEADED PETROL
(see UNLEADED PETROL)

LPG
Liquified Petroleum Gas, or LPG, is an alternate fuel which is almost universally used in taxis in Australia but has never really hit it off with private motorists outside of Victoria.

LPG cuts fuel bills by around 50 per cent. The cost of the gas varies considerably from state to state, with Victoria generally having the cheapest fuel. There is a marginal loss of performance when using LPG, but in a good installation you will probably not notice it.

Boot space is often considerably reduced because of the bulk of the gas tank and the fuel range is less. Converting a car to run on LPG costs a little over $2000 and an existing conversion can be transferred from one car to another for about $750.

Depending on fuel/conversion costs, it takes about 50,000 - 60,000km to break even on the initial outlay.

MULTI-VALVE, 4-VALVE
Most twin-cam engines have a multi-valve cylinder head to increase breathing and therefore combustion efficiency. Two inlet and two exhaust valves are used for each cylinder.

Occasionally, a single overhead cam engine also has a multi-valve layout, generally with three valves per cylinder, though some do have four per cylinder. To add further complication, some older twin-cam engines only have two valves per cylinder.

As a further complication, a few late-model car engines have five valves per cylinder, three inlet and two exhaust.

OVERSTEER
Oversteer means the car tends to turn too tightly into a corner - the tail slides to the outside of the bend. In extreme cases, the car goes sideways and then backwards. This can lead to the car hitting an obstacle sideways - where it has least strength and space for occupant protection.

Oversteer isn't common in modern cars and there really isn't space here to describe the intricacies of controlling it. If you have a car which is a potential oversteerer, get yourself a book on driving or contact an advanced driving school.

Understeer (see separate entry) is generally considered safer for everyday drivers than is oversteer.

POWER STEERING
Power-assisted steering makes the steering lighter and cuts the amount of steering wheel movement needed to turn the car through a given angle. The car is easier to drive and park - especially park.

Power steering is very common in new cars these days, even on small cars. This is due mainly to the extra steering effort that is required because of the weight of the engine over the front wheels due to front-wheel drive. It is also due to wider tyres now being fitted.

QUAD CAM
(see TWIN CAM)

SPLIT-FOLD REAR SEATS
All hatchbacks and station wagons, and an increasing number of sedans use split-fold rear seats. Many cars now have what's called a 60/40 split, meaning that either a large part of the backrest can be folded down, increasing the luggage capacity markedly and allowing one passenger to be carried. Or, the narrow part is folded, increasing the luggage capacity by a smaller amount and permitting two rear passengers to be transported in the safety of seatbelts.

Some hatches now use the station wagon-style rear seat where the rear seat base/s can be folded forward to further increase interior room.

TORQUE
Torque (not power) is the most important component in an engine's output. We won't go into a detailed explanation but will simply say that if your car will climb a hill with a fair load on board and you don't have to change down gears too often, it has good torque characteristics. When reading car makers' brochures and road test report, look not only at the maximum figure for torque, but also at the engine revolutions per minute (rpm). For example, a typical two-litre engine might have torque of 180Nm at 3500rpm.

As a general rule, the lower the engine rpm, the better. Engine designers are forever striving to increase the torque but not increase the rpm at which the peak occurs. Naturally, there are always compromises, but the engine in a family-oriented car should ideally develop its maximum torque below 4000rpm.

TORQUE STEER
Torque steer takes place when you accelerate hard in a front-wheel-drive car. At some stage during the acceleration, a lugging may be felt through the steering wheel and the car may try to pull to one side. The effect is generally worse in a turbocharged car.

Torque steer only applies to front-wheel-drive cars and is much more noticeable in powerful ones than in those with standard engines.

Good engineering can minimise torque steer. In many newer cars, it has been virtually eliminated. Older Japanese cars generally suffered more than cars from other countries, with the possible exception of the Mini and older turbocharged Saabs.

Besides being aware that it happened, there is little you can do about torque steer other than keep a correct grip on the steering wheel.

TRACTION CONTROL
Traction control prevents a car's driving wheels from skidding under acceleration by reducing power to the wheel, or wheels, which begin to slip.

A few advanced cars have traction-control systems that sense a skid is starting to happen and try to correct it by a combination of power reduction and braking specific wheels as necessary.

TURBO LAG
A turbocharger cannot work at full power the instant you push the accelerator pedal. Instead, there is a lag of about half a second to one second (it varies from car to car and according to driving conditions) between the time you press the accelerator and the car fully accelerating. When acceleration does come "on boost", it's very strong and can take an inexperienced driver by surprise.

Turbo lag can be frustrating and is the main reason turbos have lost favour in petrol-engined cars in recent years.

If you're driving a turbocharged petrol-engined car for the first time, especially if the road is wet and slippery and the car has front-wheel drive, be cautious with the Accelerator until you get a feel for what the car is going to do.

Turbo-diesel engines are much more forgiving in their characteristics than are turbo petrol engines. So also are the modern generation of light-power turbo petrol engines. The downside of low-lag engines is a lack of exciting power delivery.

TWIN CAM, DOUBLE OVERHEAD CAM, QUAD CAM
All these terms mean exactly the same thing: that there are two camshafts above each cylinder bank. It offers a more efficient operation of the engine's breathing, therefore more performance and lower fuel consumption.

There can be some loss of drivability at lower engine speeds in a twin-cam engine. This means it could be necessary to change down a gear in some conditions when a single-cam engine could stay in the higher gear. As a general rule, the more performance-oriented the engine, the more gear changes will be necessary.

(See also MULTI-VALVE)

UNLEADED PETROL
Petrol is unleaded in its normal state. Small quantities of lead are added to increase its octane rating and therefore its combustion efficiency. Unfortunately, the lead can cause damage to health, particularly to young children living in urban areas.

Lead damages catalytic converters in unleaded petrol cars, greatly reducing their emission-controlling ability. All new cars built from February 1986 for sale in Australia must operate on unleaded fuel. It is an offence to use leaded petrol in them. Many cars built before then can operate satisfactorily on unleaded petrol.

Some cars need to run on premium unleaded petrol (PULP). This is more expensive than standard ULP, is seldom discounted and isn't available in all service stations.

UNDERSTEER
Understeer means the car tends to turn less into the corner than it should. In extreme cases, it won't turn into the corner at all; it simply ploughs straight ahead.

For the average driver, understeer is easier to control than oversteer and is generally built into a modern car's steering as a safety measure.

It doesn't start to show up until you are driving hard and can be reduced or negated by lifting your foot gently off the accelerator pedal.