Supply Chain Decision-Making of New Energy Vehicles Considering Overconfidence Under the Dual-Credit Policy

Against the background of the dual-credit policy, a core policy instrument for promoting the low-carbon and sustainable development of the automotive industry, the overconfident behavior of decision-makers in new energy vehicle (NEV) supply chains has become increasingly prevalent. This paper aims to investigate the supply chain decision-making problem of NEVs considering overconfidence under the dual-credit policy, and to explore the effects of overconfidence on the decisions, profits, consumer surplus, and environmental performance of supply chain members. A two-echelon Stackelberg game model consisting of an upstream parts supplier and a downstream vehicle manufacturer is constructed, in which an overconfidence parameter is introduced to characterize decision-makers’ overestimation of market demand. The backward induction method is employed to derive the equilibrium solutions under four overconfidence scenarios, and the theoretical conclusions are verified through numerical analysis. The results show that: (1) Overconfidence improves decision-makers’ fuel-saving R&D levels, but simultaneously raises wholesale and retail prices. (2) The supplier’s overconfidence always reduces its own profit, whereas the manufacturer can benefit from overconfidence under certain conditions. (3) The overconfidence of both parties reduces consumer surplus when the technology levels of the supplier and the manufacturer are comparable, while its marginal impact on consumer surplus varies non-monotonically with the degree of overconfidence, and it improves environmental performance in most admissible parameter ranges, thereby contributing to the environmental sustainability of the NEV industry. (4) Dual-credit policy parameters, such as the credit unit price and the standard vehicle credit of new energy vehicles, can effectively regulate supply chain decisions. Overall, overconfidence has significant and asymmetric effects on NEV supply chain decisions. Policymakers should pay attention to firms’ behavioral biases and reasonably set credit parameters, while firm decision-makers should avoid profit losses caused by overconfidence, although they may also strategically exploit overconfidence under certain conditions. These insights provide managerial and policy implications for the sustainable development of the NEV supply chain.