Internal combustion engines (ICEs) have made tremendous contributions to the economic and social development of every country in the world. Today, the main aim of ICE development is to further improve thermal efficiency and reduce carbon emissions. With the rapid development of energy-saving technologies, academia and the industrial community are paying a great deal of attention to a crop of disruptive ICE technologies. The Chinese Academy of Engineering (CAE) held the International Summit on Breakout Technology of Engines and Fuels to discuss this development trend along with potential breakout technologies. In order to further promote academic exchanges in the field of ICE research and share the latest research results, the summit cooperated with Engineering, the journal of CAE, to initiate this special issue titled ‘‘Engines and Fuels.” Professor Wanhua Su, an academician of CAE and a professor at Tianjin University, and Professor Gautam Kalghatgi, an academician of the Royal Academy of Engineering of the United Kingdom, serve as the Editors-in-Chief of this special issue. Professor Hua Zhao, an academician of the Royal Academy of Engineering, and Professor Mingfa Yao, the Director of the State Key Laboratory of Engines at Tianjin University, are the Executive Editors-in-Chief. Several prominent scholars in the field of ICE engineering are members of the Editorial Board of this special issue.

Engineering focuses on research hot spots and difficult issues in the development of engineering science and technology, and looks into the future of engineering science and technology development. This special issue includes six peer-reviewed papers written by academicians of the Royal Academy of Engineering, SAE Fellows, and other well-known scholars in the ICE field from the UK, Japan, Korea, and China. The papers published in this special issue report on the latest achievements in ICE research and cover several research directions, including advanced ICE combustion technology, hybrid ICE thermodynamic cycle and hybrid ICE power technology, co-development of low-carbon technology for fuels and engines, and integrated optimization of the ICE power system, among others.

Finally, we would like to express our gratitude to everyone who participated in compiling this special issue—including all the authors, for their contributions to this issue, and all the reviewers, for their rigorous reviews and insightful and constructive opinions. We sincerely hope that this special issue will be helpful to our readers’ research and work.