Fleet-level prospective life cycle assessment: a scoping review of methods and standards toward harmonized modelling

Abstract Purpose Life cycle assessment (LCA) is increasingly applied to evaluate long-term decarbonization pathways, e.g., in the automotive sector. While life cycle-based approaches are well established at product level, methodological concepts for prospective, fleet-level applications remain fragmented across scientific literature, standards, and policy frameworks. The purpose of this review is to systematically identify, structure, and synthesize methodological building blocks relevant to fleet-level prospective LCA (pLCA) of passenger vehicles and to assess existing gaps and harmonization potential. Methods A scoping review was conducted following PRISMA-ScR principles. Peer-reviewed literature from the period 2015–2025 was systematically identified through Scopus and Web of Science and supplemented by standards, methodological guidelines, and EU regulatory documents. In total, 44 documents were identified through the systematic search. An additional 19 applied assessments, policy studies, and corporate reports were included through purposive screening, resulting in a total of 63 documents. The documents were synthesized using a concept-driven clustering approach and organized into five methodological clusters: policy and normative frameworks, core methodological foundations, fleet- and system-level modelling, foreground technology modelling and upscaling, and scenario design with background system coupling. In addition, the 19 purposively selected sources and three sources from the systematic corpus were coded according to how they operationalize the fleet. Results and discussion Most methodological elements are individually well established, yet they are not integrated in a consistent manner. The coding indicates that quantitative fleet-level results are presented using a common terminology, although they refer to at least three reference quantities that cannot be converted into one another: cohort-lifetime, stock-period, and activity-based quantities. Of the eight applications examined, only three explicitly and unambiguously state which reference quantity is used. Moreover, three corporate reports covering the same financial year delimit the respective cohort by different entry events. Neither of the two harmonization frameworks requires fleet aggregation. Additional gaps result from inconsistent temporal representation and a lack of alignment between foreground technologies and scenario-based background systems. Based on these findings, the synthesis identifies four alignment conditions, each accompanied by an indicator for detecting violations. Conclusions Fleet-level pLCA is primarily constrained by methodological integration challenges rather than by the absence of suitable methods. Harmonization can be achieved by aligning existing approaches through clearer conceptual definitions, explicit temporal assumptions, and transparent documentation of scenario dependence, without introducing new assessment frameworks. The synthesis provides a methodological basis for the consistent operationalization of fleet-level pLCA in future applied studies and framework developments.