IEA (2012), "Technology Roadmap - Fuel Economy of Road Vehicles", IEA, Paris https://www.iea.org/reports/technology-roadmap-fuel-economy-of-road-vehicles
This roadmap explores the potential improvement of existing technologies to enhance the average fuel economy of motorised vehicles. The roadmap’s vision is to achieve a 30% to 50% reduction in fuel use per kilometre from new road vehicles around the world by 2030, and from the stock of all vehicles on the road by 2050. This achievement would contribute to significant reductions in greenhouse gas emissions and oil use. Different motorised modes are treated separately, with a focus on light-duty vehicles, heavy-duty vehicles, and powered two-wheelers. A section on in-use fuel economy also addresses technical and nontechnical parameters that could allow fuel economy to drastically improve over the next decades. Technology cost analysis and payback time show that significant progress can be made with low or negative cost for fuel-efficient vehicles over their lifetime use. Even though the latest data analysed by the IEA for fuel economy between 2005 and 2008 showed that a gap exists in achieving the roadmap’s vision, cutting the average fuel economy of road motorised vehicles by 30% to 50% by 2030 is achievable, and the policies and technologies that could help meet this challenge are already deployed in many places around the world.