*4.2. Policy Implications*

The significance of the policies in the panel regression can be explained well by the logic behind consumers' behaviors. If the policy makers can understand what people really care about, the policy is likely to be effective. For example, we can use financial policies to encourage the adoption of EVs; however, if we cannot relieve the range anxiety of EV drivers, it will not work well. In addition to increasing the energy density of the battery, which has already been encouraged in various ways, building more fast chargers along the highway is a good choice compared to other incentives. That is

why the density of fast chargers was positive and significant in predicting EV adoption rates, especially for BEVs compared with PHEVs, because PHEVs can get refueling easily as traditional cars.

Besides, financial incentives have showed a declining marginal effect in promoting EV. Only the subsidies to BEV showed positive significance at a low level. The time we studied was the post subsidy era (2015–2018) [36], financial policies have been generous and used for years. Almost all the counties mentioned in the study had high subsidies or tax incentives from central government, not accounting for the local subsidies. The increase in subsidies will not bring as much benefit as before, just as the law of diminishing marginal utility indicates. The marginal effect is higher for the increase in infrastructures. According to the literature, chargers' density needs more attention paid during this time [8].

In the future, we should shed more light on the effect of charging infrastructures. Policymakers should focus more on the infrastructures of electric vehicles, especially fast public charging points, which is also consistent with some of the literatures [5]. Shown in a recent review summarizing the top antecedents in related studies, the first was charging infrastructure [13]. Many studies also highlighted the importance of fast chargers, especially in densely populated areas [37,38]. Apart from public chargers, private chargers have also played an important role in creating a favorable EV ecosystem [39,40]. Thus, policies related to vehicle–to–grid, wireless charging, and the use of technology can further increase the likelihood of EV adoption [41,42].

Besides, use–based incentive policies designed for the convenience of EV users, such as free parking policy, toll tax exemption and highway lane excess, all showed significance in the pooled regression in this study. The zero–emission mandate is also proved to be relatively effective both in this study and in related literatures. Even policies like the purchasing restriction of fuel cars in China showed a certain level of significance for EV adoption. These policies are not the most widely discussed topics in the literatures, while they are quite effective in reality and worth considering by policymakers.

**Author Contributions:** Conceptualization, J.Y., S.X. and X.M.; Data curation, J.Y.; Formal analysis, J.Y.; Funding acquisition, S.X. and X.M.; Investigation, J.Y.; Methodology, J.Y.; Resources, S.X.; Supervision, S.X. and X.M.; Visualization, J.Y.; Writing—original draft, J.Y.; Writing—review & editing, S.X. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** We would like to express our gratitude to all those who helped us during the writing of this paper, especially Ma, our supervisor, for his constant encouragement and guidance.

**Conflicts of Interest:** The authors declare no conflict of interest.

## **Appendix A**




**Table A1.** *Cont.*
