Taking carbon footprint as the signal of production quantity, it creates the signaling game model of pricing between firm and consumer. By graphic analysis tools, such as indifference curve, it researches deeply the equilibriums of the model, such separating, pooling and hybrid equilibriums. The results show that there exists the only equilibrium in the case of low tech firm(LTF) does not envy high tech firm(HTF). while LTF envying HTF, there exist separating, pooling and hybrid equilibriums. But pooling and hybrid equilibriums are not robust. They cannot be realized without the aid of external forces, such as regulations and administrative powers. The separating equilibrium is self enforced, and the emission reduction at the separating point is larger than that in the case of no envy. So it is advantageous to emission reduction. The research is meaningful for firm's decision on carbon footprint and pricing especially in the market scenario that carbon label can be used as the signal of product quantity.

To achieve dual-carbon goals and advance the sustainable development of the automotive industry, China’s Dual-Credit Policy serves as the core long-term mechanism for the low-carbon transition of the automotive industry. Given the coexistence of fuel vehicles (FVs) and new energy vehicles (NEVs) in China, existing research often overemphasizes production output while neglecting energy consumption control, and focuses predominantly on NEVs at the expense of FV optimization. To address these gaps, this paper treats FV fuel consumption and NEV energy efficiency as core endogenous decision variables. We construct profit-maximizing optimal production decision models for both types of manufacturers under the Dual-Credit Policy. Through mathematical derivation, numerical simulations, and empirical tests using actual industrial parameters, this study verifies the existence and uniqueness of optimal solutions. It clarifies the influence mechanisms of policy and market factors on corporate energy decisions and identifies the rules of strategy dominance. The findings reveal that the optimal fuel consumption decisions of FV manufacturers exhibit distinct piecewise patterns and critical threshold effects. Specifically, credit prices, NEV quotas, and fuel consumption standards determine the dominance of compliant (low-consumption) versus non-compliant (high-consumption) strategies. Furthermore, the policy exerts a significant market-oriented positive incentive on the energy efficiency upgrading of NEV manufacturers, with credit prices, market demand, and R&D costs acting as core constraints. Notably, the transition-guiding effect of the policy has clear effective boundaries, and its efficacy highly depends on the alignment between parameter design and market conditions. This research provides theoretical support for manufacturers to formulate energy-optimized production decisions and offers actionable references for the continuous optimization of the Dual-Credit Policy system and the sustainable low-carbon transformation of China’s automotive sector.