There are two types of emissions that impact on the environment, air quality and human health: greenhouse gas emissions and air pollutant emissions.
Greenhouse gas emissions, such as carbon dioxide (CO2), trap heat from the sun in the earth’s atmosphere, causing the ‘greenhouse effect’ and climate change. CO2 is the main greenhouse gas produced by motor vehicles.
Air pollutant emissions emitted by motor vehicle exhausts include:
- carbon monoxide (CO),
- nitrogen oxides (NOx),
- particulate matter (PM); and
- volatile organic compounds (VOC).
These emissions can cause smog, heart and lung disease and cancer.
Greenhouse Gas Emissions
Motor vehicle exhausts also produce greenhouse gases that contribute to climate change. The main greenhouse gas produced by vehicles is carbon dioxide (CO2), but they also produce nitrous oxide and methane. Light vehicles account for around 11 per cent of Australia’s greenhouse gas emissions.
The Department of Climate Change, Energy, the Environment and Water maintains Australia's National Greenhouse Accounts which has more information on the emissions of greenhouse gases in Australia.
On the Green Vehicle Guide (GVG), a higher CO2 number means a car emits more carbon dioxide (CO2) from its tailpipe. All new vehicle models up to 3.5 tonnes gross vehicle mass sold in Australia must have their fuel consumption and the CO2 emissions tested before they are sold in Australia.
The test produces three figures for fuel consumption and CO2 emissions - the ‘combined’, 'urban' (low speed) and 'extra-urban' (higher speed) values. The combined CO2 value is used to rank vehicles on the GVG website. This information is also on the Fuel Consumption Label on the windscreen of new vehicles. A vehicle's that uses more fuel will generally emit more CO2.
In 2019, the average new light vehicle sold in Australia produced 181 grams of CO2 per kilometre (g/km).The National Transport Commission estimates that if Australian consumers bought the most efficient vehicle in its class, CO2 emissions for new light vehicles would be per cent lower.
Air Pollutant Emissions
Air pollutants can cause smog and adversely affect human health. Further information on these impacts is available from the Department of Climate Change, Energy, the Environment and Water.
Motor vehicles remain a major source of air pollutants, especially where there is more traffic. However, many vehicles have cleaner exhausts that produce less air pollutants than others.
Vehicles that meet a higher air pollution standard (‘Euro level’) produce less air pollutants than equivalent vehicles meeting a lower standard. The air pollution standard section of the results page advises the air pollution/‘Euro’ standard a vehicle model meets in Australia.
The current minimum standard for new light vehicles in Australia is ADR 79/04, which is based on an international standards called ‘Euro 5’. Standards. Many vehicles sold in Australia meet tougher Euro 6 standards adopted in other countries.
- Euro 6 diesel vehicles emit less oxides of nitrogen (NOx) than Euro 5 diesel vehicles.
- Euro 6 petrol vehicles emit less fine particles than Euro 5 petrol vehicles.