Planetary gears (PGs) have been used in power-split hybrid and plug-in hybrid vehicles, sometimes with clutches to enable multimode operations. Chevrolet Volt is a well-known production vehicle using such technologies; it achieves excellent performance in both charge-depleting (CD) and charge-sustaining modes. In this paper, a detailed analysis of the General Motors (GM) Voltec powertrain used in the 2016 Chevrolet Volt (Volt Gen 2) is presented. We search through a large topological space, which includes a total of around 1 million design candidates to find different powertrain layouts that achieve the same or better acceleration and fuel economy in comparison with the benchmark: a simulated Volt Gen 2. The key technologies enabling such large-scale design exercise are discussed, and preliminary findings are reported. The case study results show that 49 designs achieve better charge-sustaining, CD, and launching performances than the benchmark, which clearly demonstrated the value of the proposed design methodology.