The second part of the paper "Hybridization of powertrain and downsizing of IC engine" presents an extensive analysis and parametric study of hybrid powertrain parameters for different drive cycles and electric energy storage devices as well as the results of vehicle dynamics. The analysis is based on the simulation model and analytical groundwork presented in Part 1. Very good agreement of the simulation and analytical results gives confidence in the accuracy of the performed analysis. Thus, the combined simulation and analytical analysis enables deep insight into the energy flow and energy loss phenomena in hybrid powertrains and reveals the advantages and disadvantages of hybrid powertrains running under different operating conditions. The analysis covers a broad range of parallel hybrid powertrain configurations spreading from mild- to full-hybrids. The aim of this paper is to indicate the influencing parameters that lead to an optimal combination of hybrid powertrain components in order to achieve an improved fuel economy of hybrid powertrains with the emphasis on drive cycle load as well as component sizes and efficiencies. It is shown in the paper that parallel hybrid powertrains exhibit considerable potential for higher energy conversion efficiency compared with conventional powertrains if their constituting components are sized adequately. (C) 2007 Elsevier Ltd. All rights reserved.