Assessing Plug-in Electric Vehicle Adoption: Methodologies, Policy Effects, and Diverging Market Pathways in China, the U.S., and Europe

Accurate projection of Plug-in Electric Vehicle (PEV) market sales share is vital for evidence-based policymaking, yet existing studies employ diverse and often fragmented methodologies, creating a need for a systematic review to clarify their analytical foundations and comparative strengths. This study classifies mainstream approaches to market projections into theory-driven and data-driven categories and reviews the merits, limitations, and future directions of five representative models. Analysis reveals that leading approaches increasingly employ cross-scale model coupling, theory-data fusion, and modular design to harness complementary strengths, improving model robustness and predictive accuracy. Furthermore, the study compares PEV policies and market outlooks in China, the United States, and Europe—the world's three largest automotive markets. The findings indicate a strong linkage between projection convergence and policy stability. China demonstrates the highest policy consistency and institutional consensus, with an average projected PEV share of new-vehicle sales of 81.3% by 2030. Europe's projections average 62.8%, driven by binding emissions mandates, whereas the U.S. exhibits greater uncertainty, averaging 31.1% amid fragmented regulations and policy uncertainty. These disparities highlight the decisive role of policy coherence and regulatory predictability in shaping PEV market outlooks.