The transport sector is supported by the continuous provision of energy and material flows and material stocks. However, most resource accounting methods do not assess the role of material accumulation in the delivery of mobility, as a service. Using a UK-based case study, we evaluate the service contribution of both resource stocks and flows in the provision of the passenger-kilometres (pkm) travelled nationally by UK-registered cars between 1960 and 2015. For flows we considered diesel and petrol. For stocks we considered steel, aluminium, and plastics, among others. We used six indicators to analyse the interactions between stocks, flows and service. Our results show that the fuel efficiency of cars increased from 0.46 to 0.69 pkm/MJ over the period. However, there was a decrease in stock efficiency from 24.9 to 17.1 pkm/kg-year. Resource productivity increased from 0.42 to 0.61 pkm/MJ. Stock expansion rate decreased from 0.16 to 0.03 year⁻¹ while the specific CO₂ embodied impact reduced from 2.4 to 2.0 tCO₂/tonne of resource flow. Consumer preferences for heavier larger vehicles and sociodemographic changes linked to workplace expectations, commuting and urbanisation patterns are key factors influencing UK car stock efficiency. While fuel efficiency has improved and will continue to do so via the mass adoption of electric vehicles, due to policy and legislative developments, there are still sustainability concerns linked to their heavier weight and the environmental impact of their increased material complexity.

能源和物质流以及物质库存的持续供应为运输部门提供了支持。然而，大多数资源核算方法并未评估物质积累在提供流动性（即服务）中的作用。使用基于英国的案例研究，我们评估了资源存量和流量在提供 1960 年至 2015 年间英国注册汽车在全国行驶的乘客公里 (pkm) 方面的服务贡献。对于流量，我们考虑了柴油和汽油。对于股票，我们考虑了钢、铝和塑料等。我们使用六个指标来分析存量、流量和服务之间的相互作用。我们的研究结果表明，汽车的燃油效率在此期间从 0.46 提高到 0.69 pkm/MJ。然而，库存效率从 24.9 下降到 17.1 pkm/kg-年。资源生产率从 0.42 增加到 0.61 pkm/MJ。库存扩张率从 0.16 年下降到 0.03 年^-1，而具体的 CO ₂体现的影响从 2.4 减少到 2.0 tCO ₂ /吨资源流。消费者对重型大型车辆的偏好以及与工作场所期望、通勤和城市化模式相关的社会人口变化是影响英国汽车库存效率的关键因素。虽然燃油效率已经提高，并将继续通过电动汽车的大规模采用来提高，但由于政策和立法的发展，仍然存在与其更重的重量和材料复杂性增加对环境的影响有关的可持续性问题。