Worldwide, the automotive industry is being challenged to make dramatic improvements in vehicle fuel economy. In Europe there are CO₂ emissions penalties prorated by the degree to which vehicles exceed mandated CO₂ levels. In the United States, vehicle fuel economy targets set by Congress in 2007 for 20 per cent fuel economy improvement by 2020 are now being accelerated by the Obama administration to 35.5 mpg by 2016 for a passenger car. Taking effect in 2012, the new rules set more aggressive fuel economy measures that will require significant gains in engine and driveline efficiency, better performance cabin climate control and the introduction of electric hybridization. This 2nd Edition of Propulsion Systems for Hybrid Vehicles addresses the electrification innovations that will be required, ranging from low end brake energy recuperators, idle-stop systems and mild hybrids on to strong hybrids of the power split architecture in both single mode and two mode and introducing new topics in plug-in hybrid and battery electrics. Important topics of the 1st Edition are retained and expanded and some outdated material has been replaced with new information.