A generalized framework for analyzing car lifetime effects on stock, flow, and carbon footprint

This study proposes a new framework for estimating the effects of changes in the physical lifespan (PHL) of cars and the possession lifespan (POL) of new and used cars on stock, flow, and carbon footprint (CF). Applying this framework to all new and used cars registered in Japan from 1990 to 2016 showed that a 10% extension of the PHL of cars reduced the CF of cars by 30.7 Mt, while a 10% extension of the POL of new cars reduced the CF of cars by 26.4 Mt, and a 10% extension of the POL of used cars produced a 5.2 Mt CF reduction. On the other hand, a 10% lifetime reduction in the three cases increased CF by 42.2, 29.4, and 6.0 Mt, respectively. These results indicate that increasing the lifetime of new and used cars could contribute significantly to the mitigation of global warming. To achieve a large reduction in life cycle emissions, car designers should focus on ways to extend vehicle lifetimes.