The Road Ahead : April May 2008
12 APR/MAY 08 STORY BARRY GREEN According to the Federal Government's Green Vehicle Guide (www.greenvehicleguide.gov.au), only the Toyota Corolla features in both the top 10 seller and top 10 'green performer' lists. The Corolla, Australia's second largest selling car behind the Holden Commodore, is rated No. 8 among the most efficient 'greenies'. Only three vehicles rate five GVG stars: the Toyota Prius, Fiat Punto and Citroen C3. The Commodore earns a very average three stars. So how do the GVG star ratings come about? All new vehicle models up to 3.5 tonnes gross vehicle mass sold in Australia are tested to determine both the fuel consumption and the level of carbon dioxide (CO2) emissions. CO2 is the main greenhouse gas emitted by motor vehicles. The level of CO2 emissions is linked to the amount of fuel consumed and the type of fuel used. This information is displayed on a fuel consumption label attached to the windscreen of new vehicles. GVG testing is conducted using Australian Design Rules (ADR) compliance information supplied directly by vehicle manufacturers. The GVG's overall star rating is based on tailpipe emissions, with equal weighting given to both air pollution and greenhouse emissions. A combined GVG rating (out of 20) is then translated into the overall star rating. For a vehicle to achieve five stars, it must have scored a combined 16 points or better. Diesel vehicles score better than petrol vehicles on fuel efficiency and produce lower levels of greenhouse emissions, but are marked down on air pollution, which includes carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx) and particulate matter (PM10). These pollutants are emitted in small quantities but can cause a range of adverse health affects. The increasing sophistication of catalytic converters, along with improving fuel standards, is helping to reduce the air pollution and toxic emissions of cars. The catalytic converters are placed in the exhaust system to convert various emissions into less harmful types, using a combination of platinum, palladium and rhodiunm as catalysts. Hybrids growing Increasingly, hybrid petrol-electric engines are being seen as cleaner and more efficient than diesel and petrol vehicles. A key benefit is that hybrids can store the energy otherwise lost as friction and heat when braking, and re-use this energy to help accelerate the car again. This allows hybrids to be much more efficient for congested urban driving but also means their benefits are much less in rural and highway driving. The downside is that hybrids are more expensive to purchase than petrol vehicles, a cost which takes a long time to recover through day-to-day running expenses. A relatively new development is the diesel hybrid. In 2006, Ford unveiled such a concept car at the the Detroit motor show, called the Reflex. This all-wheel-drive concept used a combination of diesel engine, electric motor and solar panels. If Ford's claimed 65 miles to the gallon (3.6-litres/100 km) for the Reflex can be achieved in everyday motoring, then the diesel-hybrid could have a real future. features Getting G Australia's favourite cars are not necessarily our greenest cars.
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