<p>Against the backdrop of China’s dual-carbon strategy, it is of vital practical importance to delve into the existence of a green paradox in new energy vehicles and its underlying causes. In response to this, this article expands the theory of life cycle assessment and, based on the expanded life cycle assessment theory, establishes a dynamic simulation model. From the perspectives of carbon emissions per vehicle and carbon emissions of road vehicles, it meticulously explores the “green paradox” effect of new energy vehicles under different usage lifespans and support levels. The results indicate that, from the perspective of a single vehicle’s carbon emissions, the “green paradox” effect exists in battery electric vehicles only when resource characteristics are overlooked and the average annual carbon dioxide emissions are used as the evaluation metric. Additionally, an analysis of road vehicle carbon emissions indicated that advancements in battery technology and supportive automobile purchase strategies can contribute to the emergence of a “green paradox” in new energy vehicles. Specifically, the paradoxical nature of battery technology lies in the fact that technological advancements alone cannot significantly enhance the substitution effect of new energy vehicles in the short term. Likewise, the paradoxical nature of support strategies stems from the fact that, due to environmental carrying capacity constraints, the increasing number of vehicles can negate the emission reduction benefits conferred by new energy vehicles. Based on these insights, this article further delves into the optimization pathways for new energy vehicles to contribute to the achievement of China’s dual-carbon targets for road vehicles.</p>