Product Carbon Footprint Rules Shape Declared Emissions of Electric Vehicles and Traction Batteries

Product carbon footprint (PCF) rules are increasingly used in disclosure, subsidies, procurement, and emerging performance requirements, but their interpretation and policy effects depend on accounting-rule design. We compare China's draft PCF standards for traction batteries and passenger cars, the draft EU delegated-act methodology for electric-vehicle batteries, and the French environmental-score carbon-footprint method against a harmonized analytical reference. A parametrized vehicle-battery model evaluates 50 paired configurations across four production-market pathways. Relative to the reference, China's battery rule differs by -8% to + 11% in accounted life-cycle carbon emissions, the EU battery rule yields 11-21% lower values, China's vehicle rule remains within 4%, and the French method yields 57-80% lower values, mainly because its production-focused boundary excludes vehicle use and end of life. For China-origin products entering the EU and France, destination-market rules increase mean imported-local gaps from 32% to 89% for batteries and from 8% to 96% for vehicles, with background-data choices dominating the added divergence. Functional-unit choices alter normalized PCF comparisons and the product attributes favored, while mitigation benefits from recycling and powertrain-efficiency improvements depend on rule design. These results highlight the need for transparent data governance, clearly defined reporting bases, and common reference or conversion frameworks for cross-regional PCF interpretation.