Resource and Climate Implications of China's Passenger Vehicle Fleet Transition to 2050

China's rapid expansion and electrification of its passenger vehicle fleet will strongly influence global resource demand and greenhouse gas emissions. Yet existing projections rarely capture the complex, coupled effects of vehicle- and battery-related variables alongside fleet growth and decarbonization pathways. Here, we develop a bottom-up fleet stock model with exogenously specified powertrain adoption pathways to quantify China's passenger vehicle stock and its greenhouse gas, energy, and material demand through 2050. The model is parametrized with China-specific data, evaluated against recent fleet statistics, and complemented by Monte Carlo, Sobol, and reference-scenario sensitivity analyses. We project that China's passenger vehicle stock increases from 218 million in 2019 to 360-520 million by 2050, while life cycle greenhouse gas emissions, energy use, and material demand generally peak around 2035-2040 before stabilizing or declining. Depending on future behavioral and technological pathways, final energy demand and life-cycle greenhouse gas emissions range from approximately 53% below to 122-153% above the reference scenario. Sobol analysis shows that rebound effects account for 50-73% of output variance, followed by passenger travel demand (23-29%), whereas the timing of internal combustion engine phase-out contributes less than 0.5%. These findings demonstrate that a sustainable transport transition in China requires coordinated action on demand management, vehicle efficiency, electricity decarbonization, and material stewardship.