Executive summaryInternal combustion (IC) engines operating on fossilfuel oil provide about 25% of the world’s power (about3000 out of 13,000 million tons oil equivalent peryear—see Figure 1), and in doing so, they produceabout 10% of the world’s greenhouse gas (GHG) emis-sions (Figure 2). Reducing fuel consumption and emis-sions has been the goal of engine researchers andmanufacturers for years, as can be seen in the twodecades of ground-breaking peer-reviewed articles pub-lished in thisInternational Journal of Engine Research(IJER). Indeed, major advances have been made, mak-ing today’s IC engine a technological marvel. However,recently, the reputation of IC engines has been dealt asevere blow by emission scandals that threaten the abil-i...