ABSTRACT
In recent years, improving the efficiency of automotive powertrains has attracted much attention since, among total energy consumption in the world, transportation energy use has amounted to more than 26%, and as reported by [1], road vehicles account for three-quarters of the total transportation energy (Figure 1.1). Moreover, 95% of the transportation energy comes from oil-based fuels, largely diesels and gasoline. Although a lot of alternative vehicles such as hybrid electric vehicles and plug-in hybrid electric vehicles have been marketed, more than 85% of road vehicles still load combustion engines on the powertrains. As predicted in [2], this situation will be continued, and more than 85% of road vehicles will load combustion engines within the coming 30 years [2].
