The secondary research process involved comprehensive analysis of regulatory databases, industry publications, automotive journals, and authoritative transportation organizations. Key sources included the US Department of Transportation (DOT), National Highway Traffic Safety Administration (NHTSA), Environmental Protection Agency (EPA), European Environment Agency (EEA), International Energy Agency (IEA), International Council on Clean Transportation (ICCT), Society of Automotive Engineers (SAE International), Automotive Research Association (ARA), China Association of Automobile Manufacturers (CAAM), Society of Indian Automobile Manufacturers (SIAM), Japan Automobile Manufacturers Association (JAMA), Korea Automobile Manufacturers Association (KAMA), World Economic Forum (WEF) - Future of Mobility, International Organization of Motor Vehicle Manufacturers (OICA), BloombergNEF, Cox Automotive, Edmunds, Kelley Blue Book (KBB), Black Book, Manheim (Cox Automotive), European Automobile Manufacturers' Association (ACEA), Transport & Environment (T&E), California Air Resources Board (CARB), US Energy Information Administration (EIA), Eurostat Transport Database, UN Environment Programme (UNEP), and national transport ministry reports from key markets. These sources were used to collect vehicle registration statistics, battery technology data, residual value analysis, charging infrastructure deployment, regulatory compliance data, and market landscape analysis for battery capacity segments (less than 20 kWh to over 100 kWh), vehicle types (passenger cars, commercial vehicles, two/three-wheelers), range categories, vehicle age demographics, and battery health classifications.