Are UK cars becoming more resource efficient? (1960–2015)

What is it about?

This paper evaluates how efficiently UK cars have used energy and materials to provide passenger mobility between 1960 and 2015. Instead of looking only at fuel consumption, the study combines energy flows (petrol and diesel) and material stocks (steel, aluminium, plastics, rubber, glass) to assess how they interact to deliver passenger-kilometres. It applies six resource-efficiency indicators — including fuel efficiency, stock efficiency, resource productivity and embodied CO₂ impact — to understand long-term trends in mobility, material accumulation, and sustainability.

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Photo by Francesco Zivoli on Unsplash

Photo by Francesco Zivoli on Unsplash

Why is it important?

Transport sustainability debates often focus only on fuel efficiency. This paper shows that while fuel efficiency improved (from 0.46 to 0.69 pkm/MJ), material stock efficiency declined significantly due to heavier vehicles, increased car ownership, and lower occupancy rates. In other words, cars became more energy efficient but less material efficient. This highlights trade-offs between energy savings and material accumulation and shows why sustainable mobility must consider both stocks and flows — not just fuel use.