The book "4th International Conference on Ignitio" offers a comprehensive analysis of the challenges and developments in the field of internal combustion engines, particularly regarding the increasing electrification and the demands for reducing carbon emissions. Given the forecasts predicting a rise in new registrations of vehicles with internal combustion engines by 2030, the necessity of optimizing existing technologies and developing new approaches is emphasized. The focus is on innovative ignition processes and the application of the Miller combustion cycle, as well as highly diluted combustion, to achieve efficiency values exceeding 40%. The book is aimed at professionals and students in the field of mechanical engineering and technology who wish to engage with the latest developments in engine technology.