Solving energy and environmental problems is one of the main challenges facing modern society. Transport and mechanical engineering should be involved in its implementation to the maximum extent possible. The results of scientific discussions and management decisions regarding the future of internal combustion engines determine the conceptual provisions, directions of design improvement, and the degree and quality of decarbonisation of the energy sector as a whole. The article uses a systematic approach to examine the trends in the use of internal combustion engines as a necessary part of climate-neutral transport. These problems are considered from the following aspects: the need to transition from the use of fossil energy sources to the large-scale use of RES; the objective contradiction between the use of RES and the universal use of electric vehicles as electricity consumers; the introduction of ICEs that leave a carbon footprint into technological cycles to support a climate-neutral transport industry based on RES; ways to implement the concept of a circular carbon economy that meets the requirements of climate-neutral energy while maintaining the processes with a carbon footprint. The long-term prospects for the use of transport internal combustion engines are built on this basis.