Transport: Buying the right car

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Whether you're in the market for a brand new Ferrari or a second-hand Nissan Micra, a motor vehicle represents a serious financial investment. But it's also an investment in the safety of your passengers and the health of your environment.

We all want to get the best bang for our buck when buying a car. In the 70s, a big engine might have been important. These days it is more likely to be safety, fuel economy and, increasingly, air pollution and carbon dioxide emissions.

This is where rightcar.govt.nz comes in. Set up by the government, the website lists cars by make and model, and aims to get kiwis to choose safer, cleaner and more economical cars. And the good news is that smaller doesn't mean less safe.

Rightcar.govt.nz provides fuel economy data for all cars since 2005, which is the year importers were required to supply this information, and provides safety data for many vehicles manufactured since 2000.

Safety features are covered first and foremost by the crash tests carried out by Australasian New Car Assessment Program (ANCAP) on over 400 models and rated according to their performance.

Used car safety ratings are calculated from a statistical analysis of police crash reports; specifically crashes that have happened over the last 20 years in New Zealand and in five states of Australia, and scored on a five star rating system.

While not included in the ANCAP crash tests or police crash reports, it is worth taking into account the safety features built into the car, which can be seriously impressive.

They include enhanced structural strength, pre-tensioned safety belts, airbags, child restraint anchorages, pre-crash systems, head restraints, pedestrian protection systems and automatic emergency call systems.

Performance safety features can include electronic stability control, emergency brake assist, autonomous emergency braking, brakeforce distribution, ABS brakes, roll stability systems, adaptive cruise control, tyre pressure monitoring and traction control.

Further, lighting systems have improved, with emergency brake lighting, daytime running lights, blind spot monitoring, intersection collision warning, lane support systems, automatic headlights, night vision enhancement, adaptive front lighting systems and reversing collision avoidance.

New cars are sometimes also fitted with features to reinforce good driving, such as a fatigue detection and reminder system, speed alert and limiter, traffic sign recognition, following distance warning.

Rightcar.govt.nz also monitors air pollution ratings on all car models, with ratings on gases such as oxides of nitrogen, carbon monoxide and particulates. These contribute to smog and can create health problems for people.

The amount of pollutants your car emits depends on how cleanly it burns the fuel. All cars that come into New Zealand are manufactured to an emissions standard, but some are better than others. ?Cars are, again, rated by stars. Older models can be expected to perform worse than their modern counterparts on this score.

All models are also given a rating on their CO2 emissions - the gas responsible for climate change. Fuel combustion in the engine of your car emits this gas. And the amount of gas emitted is directly related to the amount of fuel used. So the more fuel-efficient your car is, the less CO2 it will produce.

A car's CO2 ranking is obtained from its fuel economy ranking. This ranking is then converted to take into account the type of fuel that the car uses, e.g. petrol (including the octane rating), diesel, LPG etc. The more stars a car has for CO2 emissions, the more environmentally friendly it is.

Converting fuel types:

Vehicle information specifies the type of fuel a car uses but it doesn't include the octane rating, e.g. 91, 95. Using the average octane rating of fuel sold in New Zealand in 2005, a car that runs on petrol is converted using these equations:

PREMIUM PETROL - L/100 km x 23.414 = CO2 grams/km
REGULAR PETROL - L/100 km x 22.847 = CO2 grams/km
PETROL (AVERAGE) - L/100 km x 22.961 = CO2 grams/km
DIESEL IS CONVERTED TOO - ?L/100km x 26.050 = CO2 grams/km??L/100 KM: Litres per hundred kilometres travelled
CO2 grams/km: Grams of carbon dioxide emitted per kilometre travelled

The annual figure is based on a vehicle travelling 14,000 km over a year

Rate your own car:

One neat feature of the rightcar.govt.nz website is that you are able to punch in your own car's number plate, and instantly get the information regarding its safety, efficiency, pollutants and CO2.

Safety ratings have a top score of five stars, while efficiency, pollution and CO2 have a top rating of six stars.

Rightcar.govt.nz was set up with assistance from the Motor Industry Association, The Australasian New Car Assessment Program (ANCAP), The Monash University Accident Research Centre (MUARC) and the Japan National Association for Safety and Victims' Aid (NASVA)