Before a road vehicle can be registered for the first time in Australia it must comply with the Motor Vehicle Standards Act 1989. The Act applies to new and used imported vehicles and locally manufactured vehicles. The Act requires vehicles to meet national standards covering safety and environmental requirements. These national standards are known as the Australian Design Rules (ADRs).
Vehicles listed on the Green Vehicle Guide (GVG) website are primarily ranked on the basis of testing conducted by manufacturers in accordance with the ADR for fuel consumption labelling. Testing is conducted by manufacturers as part of the certification process for all light vehicles up to 3.5 tonnes sold in Australia.
Australian vehicle emission standards largely reflect international standards developed through the United Nations World Forum for the Harmonisation of Vehicle Regulations. These standards form the basis of vehicle emission standards adopted in Europe and many other countries, and are commonly known as the "Euro" standards.
The information used in the GVG is supplied directly by vehicle manufacturers. To ensure consistency, the information supplied to the GVG is checked against information supplied to the Department for the ADR certification process. The integrity of information submitted for the ADR certification process is verified through targeted audits by the Department.
Rankings are primarily based on tailpipe CO2 emissions. Like any manufactured product, motor vehicles can have other impacts on the environment. For example the vehicle manufacturing process and the level of recyclability of vehicle components can impact on the environment, as can emissions from the refining of different fuels. Data on these elements is not available from an objective source at an individual vehicle level.
The main greenhouse gas emitted by motor vehicles is carbon dioxide (CO2). The level of CO2 emissions is linked to the amount of fuel consumed by the vehicle, and the type of fuel used. All new vehicle models up to 3.5 tonnes gross vehicle mass sold in Australia are tested in accordance with Australian Design Rule (ADR) 81/02 to determine both fuel consumption and CO2 emissions. This information is displayed on a Fuel Consumption Label attached to the windscreen of new vehicles. Externally chargeable (electric and ‘plug-in’ hybrid) vehicles have an energy consumption label, which also provides information on their electric energy consumption and range. This data, along with information on the vehicle’s certified air pollution standard (from the ADR 79 test) and data provided from the ADR 83/00 stationary noise test is submitted by manufacturers (on a voluntary basis) for publication on the GVG website.
Vehicles published on the GVG website vehicles are then ranked as follows:
In the first instance, vehicles are ranked by combined tailpipe CO2 emissions (lowest to highest). In cases where combined tailpipe CO2 emissions are equal, vehicles are then ranked by urban CO2 emissions (lowest to highest), followed by extra urban CO2 (lowest to highest), energy consumption (lowest to highest), electric range (highest to lowest), air pollution standard (highest to lowest), noise (lowest to highest). Where all results are equal vehicles can then be ranked in alphabetical order (by make (A-Z), model (A-Z) and variant (A-Z).
All vehicles are tested to the same test procedure (drive cycle) under carefully controlled conditions in specialised vehicle emission laboratories. The test methods used for determining exhaust emissions and fuel consumption are specified in the ADRs. The same drive cycle is used for determining air pollutant emissions, CO2 emissions and fuel consumption. The ADRs adopt the test methods from the relevant regulations adopted through the United Nations World Forum for the Harmonisation of Vehicle Regulations (UN R83 and UN R101).
As the results displayed in the GVG are based on a standardised drive cycle, different vehicle models can be compared with confidence. However, no test can simulate all possible combinations of conditions that may be experienced on the road. Real world emissions and fuel consumption may vary from the results provided in the Green Vehicle Guide, depending upon a number of factors including driving and road conditions, driver behaviour and the condition of the vehicle.