全球对运输能源的需求巨大且不断增长，主要由在内燃机（ICE）中燃烧的石油衍生液体燃料来满足。此外，未来对航空燃油和柴油需求的增长速度预计将快于对汽油的需求，可能会使低辛烷值汽油更容易获得。许多重大措施力争发展电池电动汽车（BEV）和燃料电池作为内燃机汽车的替代品，并寻求如生物燃料和天然气等燃料作为传统液体燃料的替代燃料。然而，这些替代方案中的研究基础都非常薄弱，并且还要克服重大障碍从而快速自由地发展。因此，在未来几十年内，运输（特别是商业运输）将继续主要由燃用石油基液体燃料的内燃机提供动力。因此，只有通过改进内燃机才能确保交通运输的可承受性、能源安全，控制对温室气体（GHG）排放和空气质量的影响。实际上，内燃机在使用目前市场上燃料的同时，通过改进燃烧系统、控制系统和后处理系统，以及在部分电气化混动辅助下将进一步得到改进。然而，通过改进燃料/ 发动机系统，内燃机依旧还有很多发展空间，可以使我们更多地利用制造燃料过程中的收益并使用易于获得的部件。如汽油压燃（GCI），可在压缩点火发动机中使用低辛烷值汽油，使汽油受压缩着火。与现代柴油发动机相比，GCI可以实现接近柴油机的效率，且在成本更低的情况下较易控制氮氧化物（NO_x）和颗粒物的排放。按需辛烷值（OOD）还有助于优化燃料的抗爆性能，从而提高系统的整体效率。

The global demand for transport energy is large, growing, and primarily met by petroleum-derived liquid fuels powering internal combustion engines (ICEs). Moreover, the demand for jet fuel and diesel is projected to grow faster than the demand for gasoline in the future, and is likely to result in low-octane gasoline components becoming more readily available. Significant initiatives with varying motivations are taking place to develop the battery electric vehicle (BEV) and the fuel cell as alternatives to ICE vehicles, and to establish fuels such as biofuels and natural gas as alternatives to conventional liquid fuels. However, each of these alternatives starts from a very low base and faces significant barriers to fast and unrestrained growth; thus, transport—and particularly commercial transport—will continue to be largely powered by ICEs running on petroleum-based liquid fuels for decades to come. Hence, the sustainability of transport in terms of affordability, energy security, and impact on greenhouse gas (GHG) emissions and air quality can only be ensured by improving ICEs. Indeed, ICEs will continue to improve while using current market fuels, through improvements in combustion, control, and after-treatment systems, assisted by partial electrification in the form of hybridization. However, there is even more scope for improvement through the development of fuel/engine systems that can additionally leverage benefits in fuels manufacture and use components that may be readily available. Gasoline compression ignition (GCI), which uses low-octane gasoline in a compression ignition engine, is one such example. GCI would enable diesel-like efficiencies while making it easier to control nitrogen oxides (NO_x) and particulates at a lower cost compared with modern diesel engines. Octane on demand (OOD) also helps to ensure optimum use of available fuel anti-knock quality, and thus improves the overall efficiency of the system.