Choosing a safe and sustainable car

The basics

Adjustability and comfort

Vehicle fittings must be able to be easily adjusted so you are comfortable and in control on the road. All adjustments should 'lock' in place until you want to change them.

Air-conditioning

You should be able to adjust the temperature and ventilation to suit weather conditions. Air conditioning helps prevent fatigue by keeping you comfortable and also demists the windows in wet or humid weather. Air conditioning provides real safety benefits; however, using it will increase fuel consumption. At speeds of less than 80 km/h it may be more fuel efficient to open car windows instead.

Head restraints

Head restraints can protect your head from whiplash by supporting it in a crash. They should preferably be fitted to all seats - front and back. Head restraints must be permanently fixed or adjustable to a position high enough and close enough to the back of the head to provide support for taller people. See active head restraints under features to protect you and others.

Seats

The driver's seat should be able to be moved forward and backward, up and down, and the seat back should recline at different angles. This helps you to be comfortable, to see well and to operate all controls easily. Many seats have an adjustable lumbar region to improve comfort further. Seats can also be designed to improve protection in a crash – see anti-submarining seats under features to protect you and others.

Steering wheel

Adjustable steering wheels can be moved forward and backward, up and down, and tilted to different angles. A correctly positioned steering wheel will help maximise your control of the vehicle. Steering wheels can also be designed to improve protection in a crash – see collapsible steering wheels under features to protect you and others.

Brakes

Good brakes are essential for safe driving, and must be well maintained. Regular brake fluid replacement is essential, as the fluid may absorb water over time, making it more likely to boil. To help with maintenance, it is better to have brakes with an open design so that wear of the lining and pads can be checked easily. Any repairs or replacements must be made to the whole axle set, not just one end of the axle, otherwise braking may be uneven and unsafe. It is also important to regularly check the condition of brake hoses and replace them as needed.

Brakes are important not only for safety but also fuel efficiency, as driving smoothly and at slower speeds uses less fuel.

With a good brake system:

• the vehicle can stop in the shortest possible distance and maintain stability
• the vehicle can be easily controlled during braking
• braking performance is consistent with pressure on the brake pedal.

Drum brakes offer very good braking on the rear axle, but are not as effective on the front axle. When disc brakes are used on the rear axle, a drum handbrake is usually incorporated.

Disc brakes offer better performance than drum brakes during long or repeated braking, and when braking at high speed. Braking hard or frequently can create high temperatures where the brake surface and frictional material touch each other. This can reduce the brake's efficiency, which is called 'brake fade'. Brake fluid can also boil under repeated braking, causing the brakes to fail altogether. The best disc brakes are ventilated - this cools the brakes and increases their resistance to brake fade.

Some modern cars have more sophisticated brake systems which can greatly improve safety. See ABS under features to prevent accidents.

Exhausts

A good exhaust system is important not only for your safety but also for the environment, as it will reduce emission of greenhouse gases and other pollutants. It will also reduce another environmental effect, noise. For the good of others, and the environment, make sure your exhaust doesn’t pollute the air with emissions, smoke or excessive noise.

- Leaky exhausts

With a good exhaust system the vehicle is sound, with no leakage of gases into the passenger compartment. For your own safety, check your exhaust has no leaks. An exhaust leak can be very dangerous. If the exhaust finds its way inside the vehicle, carbon monoxide poisoning can result. The smell of burning oil can mean a worn-out engine. If you can smell petrol fumes while you are driving, you may have an exhaust leak. This can be very dangerous, as carbon monoxide leaks can poison you and your passengers and you could pass out behind the wheel.

- Emission of pollutants and smoke

With a good exhaust system the vehicle burns the fuel efficiently, makes effective use of whatever catalysts, filters etc were installed at manufacture, and emits fewer pollutant gases that affect air quality. Keep the engine tuned and maintained. Checks for smoky vehicles are now part of the Warrant of Fitness. Some causes can be easily fixed, eg, by changing the air filter. Sometimes the vehicle may require a simple tune-up. In other cases, the vehicle’s engine condition may be more serious and require extensive repairs. You should consult a mechanic with experience in this area to ensure the most effective repair for your vehicle.

- Emission of noise

With a good exhaust system and effective silencer the vehicle does not make excessive noise when operated. An objective noise test has been developed to ensure vehicles are not excessively noisy. An objective noise test uses scientific procedures to measure noise levels. The equipment measures the vehicle's exhaust noise levels against a pre-determined standard.

Fire prevention and protection

Fire prevention and protection are important factors in vehicle safety. The fuel tank and pipe connections should be designed and positioned to minimise any likely damage in a crash. You should be aware of any fire hazards around vehicles and fuel – check there are no leaks when you fill up. Also be aware of any different fire hazards if your vehicle has an alternative fuel (e.g, CNG, LPG, biofuels).

An excess flow valve in a fuel injection system can prevent the fuel pressure pump discharging petrol if there is a rupture 'downstream' from the fuel tank. Some vehicles automatically shut off fuel flow in a crash.

In the car’s interior, flame resistant materials slow the spread of a fire.

Handling and stability

A vehicle with good handling and stability is safer to drive. The vehicle holds the road and is more responsive to the driver. This is achieved through a combination of steering, suspension, braking, acceleration, body characteristics and weight distribution.

Each manufacturer has their own system of improving vehicle stability, road-holding ability and handling performance. It is worth test-driving several vehicles to get a better idea of which one best offers you safe, efficient and comprehensive control on the road. Learn to handle your car – you’ll need control in an emergency. Be aware of any common faults such as rollover risk, and any special safety features such as traction control. Some cars have advanced features to improve handling and stability – see features to prevent accidents.

Load restraints

Load restraint is an essential consideration if the vehicle you are buying is likely to often be carrying heavy equipment or baggage, as these can cause serious injuries in a crash. Even a small object left on the parcel tray behind the back seat can become a dangerous projectile. Be particularly careful if your load contains dangerous goods as a spill can cause environmental damage.

- Vehicle boot (or trunk)

The vehicle boot should have tie-down hooks or eyes so heavy objects can be secured with rope. Ratchet-tensioned straps can also provide excellent load restraint. Station wagons in particular may have a luggage cover or net, which offers reasonable load restraint provided the material can be securely fastened and does not stretch too much.

- Stowage boxes and compartments

Plenty of stowage boxes or pockets are a real advantage. Loose items can be safely held or locked up so that they do not pose a risk. Some stowage compartments may be located under the floor, so passenger space is not reduced.

- Cargo barriers

A cargo barrier can be a vital vehicle feature for protecting people from loose loads in a crash. Cargo barriers usually have a steel tube frame, with steel mesh or polycarbonate preventing items from striking occupants. They are placed between the cargo and the front or back seat. When buying a cargo barrier ensure it meets standard AS/NZS 4034: 1994, or later standards as they are developed.

Safety belts

Safety belts (or seat belts) are one of the most crucial safety features in a car. Approved belts must be fitted in all cars, vans, utes and four-wheel drives, and it is compulsory to wear them, whether you are sitting in the front or back seats.

The safety belts must be in good condition. You should have safety belts checked immediately if:

• the buckles are not working properly
• the belt is damaged or faded
• the belt starts to fray.

Legal requirements for safety belts have changed over the years and are different depending on the age of the vehicle. The type of belt has also changed from static belts to retractor belts.

Three-point (lap and diagonal) belts must be fitted in the outer seating positions (including the driver's seat) in most cars, vans, utes and four-wheel drives. Two-point (lap) belts are legally allowed in centre seating positions, but three-point belts provide better safety.

Safety belts stop the driver and passengers being thrown from the car in a crash. They also allow the wearer to ‘ride out’ the crash, moving in the same direction and at the same time as the car, minimising the chance of collision with the interior. Wearing a safety belt can halve the risk of being injured or killed in an accident.

Safety belt technology has evolved greatly since they were first introduced. Modern belts have many features to improve their performance and maximise the level of protection they offer. These features include:

• Webbing elasticity: the belt’s webbing is designed to elongate during a crash to better cushion the wearer
• Retractors: most modern belts have retractors which both provide the wearer with an optimum fit, and keep the belt out of the way when it’s not in use. These lock automatically during a crash. ‘Active control retractors’ are more sophisticated models, which work with other in-car technologies to tighten the belt before a crash, and release it afterwards.
• Pretensioner: this is a device that removes any slack from a seat belt before it is ‘loaded’ with the force of the wearer’s weight during a crash. It is usually triggered by the restraint control module (an in-car computer that controls other protection systems) and after being triggered once, will need to be replaced.
• Load limiting: technology that works to ensure larger and heavier occupants get sufficient protection from the seat belt in a crash. Works in conjunction with the pretensioner to either ‘pay out’ more of the belt webbing, or slightly alter the way the retractor works.
• Adaptive restraints: in-car protection features that adapt to work differently depending on the size of the car’s occupants, or the type of accident. Although there is a great deal of research into this area, there are few features available yet for car buyers.

Tyres

Tyres are one of the most important safety features. Whenever a vehicle accelerates, corners or brakes, it puts force on the tyres. Good tyres grip the road, which is crucial in helping avoid crashes.

Choosing the right tyre depends on the type of vehicle and how it will be used. Tyres that suit a car used for city driving could be unsuitable for one carrying heavy loads or used off-road. The tyres fitted by the manufacturer are suitable for everyday use on most vehicles, but it’s a good idea to discuss tyre choice with the dealer or a tyre specialist.

Tyre safety & maintenance

• Choose tyres with an approved standards mark. It is illegal to use or sell tyres that do not comply with an approved standard.
• Check the tyre pressure often. This will optimise performance, load-bearing and wear, and also cut down on fuel consumption – driving on poorly inflated tyres uses more fuel.
• Having tyres of different construction or size fitted to the same axle is dangerous and illegal.
• Ideally, all tyres on a vehicle should be of the same construction, as mixing tyre types affects driving control. Tyres should be replaced in sets of four (or at least in pairs on the same axle) to maintain consistent handling. At the very least, the same type of tyre should be fitted to the same axle (front or rear).
• Every tyre has a maximum speed rating. A tyre with a high speed rating will generally grip and perform better at higher speeds than one with a low speed rating.
• A tyre has a load index that indicates its maximum carrying capacity. Ensure vehicles carrying heavy loads have tyres capable of safely bearing the weight.
• Car manufacturers recommend that replacement tyres be the same type as those originally fitted, to maintain all-round driving performance.
• If the size of a replacement tyre differs from that of the original tyre, ensure the new size is compatible with the wheel rim size and that adequate clearance exists in all conditions (including when snow chains may need to be fitted).

Choosing tyres

No tyre is perfect for all driving conditions. When choosing tyres, you should select ones appropriate for your vehicle and the kind of driving you will be doing.

Long-life tyres made of hard compounds usually last longer than softer tyres, but may not grip as well, particularly in the wet. A tyre with a big 'footprint' (the surface area in contact with the road) will provide good grip in dry conditions, but may not grip as well on wet roads.

Ideally, tyres should be renewed in sets of four. If this is not possible, tyres should at least be replaced in pairs on the same axle. Most tyre manufacturers recommend placing the tyres with the best grip and cornering power (new tyres) at the rear, whether the car is front or rear wheel drive. Fitting new tyres to the front can result in oversteer and loss of control.

Tyre size and construction

Make sure your tyres are the correct size and that they are fitted to the correct rim size. If the size of a replacement tyre differs from the original, make sure that the new size is compatible with the rim size and that there is adequate clearance for all conditions, including when snow chains may need to be fitted.

Always check with a tyre specialist before changing an original rim or tyre fitted by the vehicle manufacturer. Fitting tyres with a different diameter to the originals will affect the accuracy of the speedometer and odometer. If you fit wider wheels and tyres, an increase in wheel offset beyond 25 mm overall, will require the vehicle to be certified by a Low Volume Certifier.

Speed ratings and load capacities

Every tyre has a maximum speed rating and a load index that indicates its maximum carrying capacity. A tyre with a high speed rating will probably perform better at high speeds than one with a low speed rating. If you carry heavy loads in your vehicle, make sure it is fitted with tyres capable of safely bearing the weight. Tyres are marked with symbols that indicate their maximum speed ratings and load capacities.

Balance

No matter how well a tyre is made, its life and performance depend largely on how it is treated. Safe driving, regular inspections and rotating tyres - moving tyres around the car to help keep wear patterns even - are all essential components of good tyre care.

Correctly balanced wheels will ensure smooth and vibration-free running and improve tread life, as well as extending the life of the vehicle's suspension and steering components.

Tyre inflation

Check the inflation of all tyres - including the spare - every two weeks, while tyres are cold. Even a short trip to the garage will warm up tyres and raise the pressure. (Remember, space-saver spare tyres must be inflated to a much higher pressure than normal tyres.)

Correct tyre pressure is vital for balanced braking, maximum grip and long tyre life. Under-inflated tyres will increase fuel consumption and affect the safe handling of the car, while over-inflation can mean an uncomfortable ride and reduced grip. Both under and over-inflation will cause your tyres to wear out sooner.

Legally, tyres are required to be maintained at the pressure recommended by the vehicle manufacturer. All modern vehicles have a tyre information placard in a conspicuous place, showing the correct inflation levels for normal driving, as well as for higher speeds and maximum loads.

Tread wear

Good tyre tread is necessary to maintain road grip, especially in wet weather. Legally, for tyres fitted to most types of vehicles, the tyres must have a tread pattern of at least 1.5 mm deep in all the principal grooves of the tyre (excluding any tie-bar or tread depth indicator strip) and around the entire circumference of the tyre. The principal grooves are the ones containing moulded tread depth indicators.

Tread wear isn't the only factor that reduces grip in older tyres. As most tyres age, the rubber hardens, further reducing wet-weather performance.

Directional tyres

Some high performance tyres have directional treads. These tyres are designed to rotate in one direction only, to provide handling and performance benefits.

If these tyres are fitted the wrong way around, in the wet the tread pattern will effectively dam up water and reduce grip. When fitted facing the wrong way, directional tyres can also cause vehicles travelling at high speed to become unstable.

Tyres with asymetrical treads have tread patterns which vary across the width of the tyre and must be fitted to the vehicle as indicated on the tyre. If directional tyres are moved from one side of a vehicle to the other, the tyres must be removed from the rims and turned around to face in the proper direction.

Tyre repairs

Manufacturers have firm guidelines on which parts of a tyre can be repaired. Always check these before carrying out repairs.
Currently the law requires repairs to return tyres to 'within safe tolerance' of their state when manufactured. It’s likely that tyre repairs will be required to meet approved standards in the near future.

Many garages sell 'string repair' kits or sealants as a quick-fix solution for tyre punctures. String repair kits use a fibre cord or rubberised string-type plug pushed through from the outside of the tyre to seal a puncture. Tyre makers warn that these repairs are only good for 160 km of driving at a maximum speed of 80 km/h. If a proper repair isn't carried out, the object that caused the puncture can remain in the tread scraping out the sidewall, or water can get into the tyre's casing and deteriorate the reinforcing material. Either of these can lead to a tyre rupture or blow out.

Similar to string repairs, sealants are injected into tyres. Preventative sealants can cover over a puncture hole, but the seal will be on the inside of the tyre and the hole on the outside may allow moisture to enter the casing. This can deteriorate the reinforcing material and lead to a rupture or blow out. If a sealant is applied through the tyre's valve it can also unbalance the tyre and wheel.

A string repair kit or sealant should only be used as a temporary measure until the tyre can be removed from the wheel and repaired. Vehicles with a sealant-repaired tyre should only be driven slowly and for short distances.

Some sealants are designed to be used in new, unpunctured tyres to limit the very slow loss of air pressure that usually occurs. These sealants are not intended for use as 'get-you-home' puncture repairs, but may be effective at reducing air loss when a sharp object punctures the tyre.

Space-saver tyres

Many modern cars are equipped with temporary-use or space-saver spare tyres which are smaller and lighter than standard spares. These tyres are usually about the width of a motorcycle tyre. Space-saver tyres normally need to be inflated to a higher pressure. Make sure yours is inflated properly.

Space-saver tyres should be used only in an emergency - they are not designed to be used over long distances. Space-saver tyres have a speed restriction of 80 km/h. Your vehicle's handling may also be different when a space-saver is fitted. Drive carefully and never fit more than one space-saver tyre to a vehicle.

As long as you keep to these guidelines and your space-saver tyre is in good condition, it is safe to drive on.

Visibility, being seen and signals

- Lights

Good headlights are a crucial safety feature for driving at night and in poor light. They should give you a good view of the road and roadside without distracting oncoming traffic. Fog lamps are designed to improve visibility in fog but should only be used in foggy conditions.

Some cars have wipers or water jets to keep the headlights clean. Large, well-positioned tail lights, brake lights, high-mounted stop lamps, reverse lights and indicators let other road users know that the vehicle is there and what it is doing, so crashes are less likely to happen.
Some cars are fitted with daytime running lights, which are designed to further increase the visibility of your car. See additional features to avoid a crash.

- Windows

Windows should be a good size and allow clear vision in all directions, including a view of the vehicle's extremities. Some windows may cause glare or reflections. Blind spots created by front and rear pillars should be minimal. Tinted windows can reduce driver vision, particularly at night or in bad weather. The level and position of tinting is restricted by law, so think carefully before buying a car with tinted windows. Also consider how your ability to see could be affected if you are carrying loads.

- Mirrors

Good mirrors will help minimise the car’s blind spots and enable you to see potential hazards when reversing, parking or changing lanes. Mirrors should be easily adjustable from inside the car to suit different driving positions. Some cars have heated mirrors to stop them fogging up. Dipping interior day/night mirrors can be quickly adjusted to prevent you being dazzled by the lights of vehicles behind. You should be familiar with the characteristics of your car’s mirrors - for example, convex mirrors that reduce blind spots make vehicles appear more distant than a flat mirror would.

- Wipers and demisters

Wipers and demisters help maintain clear visibility, and should be on the front and rear windscreens. The blades should be replaced regularly to ensure the wipers work well in wet weather and also when cleaning windscreens. Demisters for side windows can further improve visibility. The most efficient demister is a good air-conditioning system.

Last updated: 16 July 2008