Australia’s obsession with larger and less efficient cars

Road transport is responsible for a substantial share of global carbon dioxide emissions. So, reducing these emissions is a high priority.  

In our new research, my colleagues and I compared the two car fleets and examined their emissions in detail. We found Australian cars are typically larger, heavier and less efficient, producing 43% more emissions than their EU counterparts. The results demonstrate the vital role of well-designed, ambitious policies and regulations in driving down emissions.  

What we did 

In collaboration with the European Commission’s Joint Research Centre, we collected information about the respective car fleets in Europe and Australia. 

We obtained region-specific vehicle specifications including vehicle sales, car make and model, weight, size, rated power, battery capacity and certified emissions performance. We extracted this from previous studies, publicly available data sets and information in Europe and Australia. 

We then fed this information into detailed simulation models to estimate emissions in a wide range of real-world conditions, for each fleet. This included the effects of different driving conditions and climates. 

What we found 

Our research revealed Australian cars are larger and heavier than EU cars, which has direct consequences for emissions. 

New vehicles in both the EU and Australia must be certified, with their fuel consumption and emissions tested against emission limits, before they can be sold. 

But the test procedure differs between the EU and Australia. The EU uses a modern procedure, whereas Australia still uses an outdated and unrealistic test developed in the 1970s – ironically called the New European Drive Cycle test. 

In the four years from 2018 to 2021, the difference between certified CO₂ emissions of new cars registered in Australia and the EU increased by 20%. This was mainly due to the more rapid rise of EVs in Europe. 

Then there’s the difference between certified emissions and what actually happens on the road, often referred to as the “gap”. We found the gap between certified CO₂ emissions and real-world emissions is larger in Australia. In Europe the average gap for petrol and diesel cars is 15–20%, whereas in Australia it is 30–35%. 

Differences in vehicle weight and size, driving style, climate, and the use of air conditioning contribute, but the outdated test protocol is a major factor. 

The gap is particularly large for plug-in hybrid electric vehicles. Plug-in hybrid electric vehicle emissions are three to four times higher on the road in both Europe and Australia. 

Why? Largely because certified emissions performance assumes these vehicles will drive in electric mode 75–90% of the time, while the reality is more like 25%. So in practice, these vehicles mostly drive around as high-emitting petrol or diesel cars. 

Overall, we estimated the real-world CO₂ emissions of the registered on road fleets in 2021 were 143 grams per kilometre for the EU and and 204 grams per kilometre for Australia. This means the average Australian car on the road is producing 43% more greenhouse gas emissions than the average EU car. 

Mandatory CO₂ emission targets work 

Our research shows mandatory CO₂ emission targets are effective in reducing emissions from both (new) passenger cars and, over time, the fleet as a whole. But this only happens if they are well designed. 

With its long-standing regulations, the EU has significantly reduced CO₂ emissions, mainly through increased sales of low- or zero-emission vehicles. Conversely, Australia has relied on ineffective voluntary emission standards so far, with relatively slow uptake of electric vehicles and slow or even no progress in reducing emissions as a result.  

As the EU shows, setting ambitious, effective and legally binding emissions targets can drive innovation and transform markets. 

But mandatory targets are not enough on their own. Complementary policies are needed, such as providing incentives to purchase electric cars, and developing charging infrastructure. This holistic approach looks beyond vehicle technology to also consider solutions such as promoting active travel, improving public transport and reducing the need for travel altogether. 

Our research also clearly shows Australia needs to update official test procedures. It’s crucial to include on-board fuel consumption monitoring in the new standard, as is done in Europe, to monitor real-world fuel/electricity use and emissions. 

Future regulations should consider incorporating the emissions over the life of a vehicle from manufacturing and fuel/energy production to recycling and disposal. 

Accurate information for consumers, as well as properly designed government policies, will help Australia finally start reducing greenhouse gas emissions from transport.