Australian motorists’ preference for more powerful vehicles that weigh more due to 4-wheel-drive and other accessories means potential reductions in fuel consumption from technological advances have not been fully realized, a recent report says.

The study by the Australian government’s Bureau of Infrastructure, Transport and Regional Economics says this is a worldwide trend in the automobile sector, and it cautions against undue reliance on technology, alone, to deliver reductions in fuel use and emissions.

New cars now are one-third more efficient than equivalent models sold three decades ago, the report finds.

“However, that said, the long-term downward trend in energy intensity has accelerated somewhat in recent years as the latest generation of more fuel-efficient light vehicles entered the market, and buyers downsized to smaller cars as (gasoline) prices rose,” the report says.

Until 2001, technological advances in engine technology, which improved fuel efficiency, were offset by increases in power, weight and the popularity of 4WD vehicles, the bureau says.

“Since 2001, the overall trend in fuel consumption has continued to decrease, with average new light-vehicle fuel consumption down 8.4% to 28.9 mpg (8.1 L/ 100 km).”

The country’s vehicle mix has seen a decrease in the proportion of passenger cars, with an increase in the all terrain wagon-SUV (ATW-SUV) category, the report says.

Between 2001 and 2008, passenger cars saw their share fall from 72% to 61%, while the ATW-SUV share rose to 20% from 15%. The light-commercial-vehicle share grew from 13% to 18%.

The report estimates average carbon-dioxide emissions from new light vehicles of about 30% over the period and says by 2008, the average CO2 emissions level for light vehicles had fallen to about 235 g/km.

The Sunday Age newspaper says the new report comes as the Australian government considers whether to follow the U.S. and introduce mandatory emissions standards for light vehicles.

The U.S. government last May opted to set average fuel consumption for U.S. vehicles at 35.5 mpg (7 L/100 km) by 2016.

The newspaper quotes Transport Minister Anthony Albanese as saying more will need to be done to reduce fuel consumption and greenhouse-gas emissions from the transport sector, including helping “Australians make more informed choices.”