A driving need for fuel economy

Readily available technologies can reduce vehicles' fuel consumption by up to 50%

19 April 2013

This article appears in the latest issue of IEA Energy: The Journal of the International Energy Agency.

Transport offers the easiest path for reducing oil dependency in theory: simple, readily available solutions promise a 30% to 50% improvement in fuel economy, depending on the country, while reducing carbon emissions by several gigatonnes of CO2 each year.

Technologies now available to reduce fuel use include better engines and transmissions, improved aerodynamics and tyres, and more efficient auxiliary power systems such as lights, heating and air conditioning. By 2020, such advances promise a 15% gain in efficiency for new vehicles powered by conventional gasoline engines: 28% for diesels and 44% for full-hybrids, the United States National Research Council says (versus a 2005 conventional gasoline vehicle). By 2035, down-sized gasoline- and diesel-engine vehicles should be nearly 50% more efficient than today, with hybrids nearly two-thirds more efficient. 

But while auto manufacturers steadily deploy new technologies in vehicles, uptake for efficiency is slow, as with hybridisation, or the gains are used for purposes other than improving fuel economy, such as increased power.

Roadblocks to higher efficiency
Several market-related barriers reduce both manufacturers’ and consumers’ incentives for greater fuel economy.

To make informed decisions, consumers need to know about the efficiency of a vehicle. Trustworthy and widespread information about fuel economy requires labelling and ratings based on improved testing methods that reflect real-world driving conditions. Owners also must accept realistic discount rates for cars to correctly calculate repayment periods.

Low prices, and especially subsidies, for fuel limit efficient vehicles’ economic return to individuals and companies, making it hard to justify any extra up-front cost. Similarly, uncertainty about oil prices can discourage buyers from purchasing more efficient vehicles.

These factors affect the payback period, with advanced gasoline engine and hybrid vehicles requiring a lengthy five-plus years. On a societal basis, however, fuel savings and forgone emissions over the average life of a car far exceed the cost of the new technology.

Educating drivers and equipping vehicles with gear-shift indicators and fuel-use displays can correct wasteful driving habits. Eco-driving measures can lift fuel economy by up to 10%. Smoother road surfaces can save up to another 10%, while better traffic flow reduces rolling resistance as well as stops and starts.

Implementing the right policies – now
In the prize-winning reports Technology Roadmap: Fuel Economy for Road Vehicles and Policy Pathway: Improving the Fuel Economy of Road Vehicles, the IEA tells how countries can encourage more efficient road transport. Some countries have long had programmes aimed at greater fuel economy, but such major OECD markets as the United States, Japan and the European Union only recently adopted strong measures. China, too, has adopted tough policies, but most other major emerging economies lack fuel economy standards, fiscal measures or even fuel economy labelling programmes.

Time is running out. It takes a government up to two years for the full analysis, stakeholder engagement and final rule-making required to plan and develop a policy. In addition, manufacturers need at least two years from the final development of the policy to respond with changes to their product plan; three to five years offer full flexibility for them to meet the requirements at a lower cost. Allowing the three to five years also permits tougher targets because manufacturers can react more effectively and improve the cost-effectiveness of their solutions.

The IEA recommends a ten-year horizon for regulation to give a clear signal for tighter standards coming in the future.

This article was written by François Cuenot, who joined the IEA Energy Technology Perspectives transport team in 2009 and heads work on the Mobility Model that helps project fuel demand and associated emissions to 2050. He also leads IEA efforts in the Global Fuel Economy Initiative and the Sustainable Low Carbon Transport partnership.


The International Energy Agency (IEA) produces IEA Energy, but all analysis and views contained in the journal are those of individual authors and not necessarily those of the IEA Secretariat or IEA member countries, and are not to be construed as advice on any specific issue or situation.

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