Who should invest in EV charging infrastructure? Policy design under ZEV mandates

Governments worldwide have implemented multiple incentive measures to promote electric vehicle (EV) adoption, including consumer subsidies, infrastructure investment subsidies, and Zero Emission Vehicle (ZEV) mandates. Motivated by these policy instruments, various stakeholders (including automakers and EV component suppliers) are actively investing in charging infrastructure. Which subsidy policy is most cost-effective, and which entity’s infrastructure investment yields optimal outcomes? This study constructs a Stackelberg game model comprising government, component supplier, and competing fuel/electric vehicle manufacturers to explore optimal policy structures under three investment modes (i.e., supplier-led infrastructure investment, EV manufacturer-led investment, and traditional automaker-led investment). We systematically evaluate the performance in minimizing government expenditure while achieving adoption targets for each investment mode. More importantly, we extend our analysis to include ZEV mandates and their impact on subsidy effectiveness and government expenditure. Our results provide several interesting and counterintuitive insights. First, we show that supplier-led infrastructure investment (i.e., Mode S) consistently achieves the lowest policy expenditure and highest social welfare. Second, when automakers invest (Modes E and F), consumer subsidies alone are never optimal, contradicting widespread policy practice. Mode S consistently achieves the lowest expenditure and highest social welfare, yet Modes E and F generate superior economic benefits for firms—revealing a fundamental trade-off between public cost-efficiency and private profitability. Third, although ZEV mandates are intended to substitute for costly subsidies and reduce fiscal burden, our analysis reveals they may paradoxically increase government expenditure and discourage EV production when requirements become overly stringent.