Can a prolonged use of a passenger car reduce environmental burdens? Life Cycle analysis of Swiss passenger cars

As a consequence of the introduction of limits on exhaust gas emissions and a target agreement between the Swiss association of car importers (auto-schweiz) and the Swiss government calling for a reduction in the specific fuel consumption, a considerable reduction of exhaust emissions of newly registered Swiss passenger cars occurred in the last 10 years. Also, for the near future an ongoing reduction of exhaust emissions of newly registered vehicles is expected. However, applying the concept of life cycle thinking, exhaust emission reductions may be outbalanced with an increase in specific car manufacturing expenditures and/or a longer use of the car. Thus, from the point of view of an individual car owner, a prolonged car use may be the environmentally preferable option. In order to investigate this question, a comprehensive analysis of the environmental performance of newly registered diesel and petrol passenger cars in the time period from 2000 to 2010 has been performed. Life Cycle Assessment (LCA) has been employed focusing on three transport components: ‘vehicle travel’ (exhaust and abrasion emissions), ‘fuel chain’ (supply of fuels) and ‘car infrastructure’ (manufacturing, maintenance and disposal of cars). The presented model aims to gain insight into the issue of longevity and prolonged car use for the Swiss case, rather than giving ultimate recommendations. The analysis focuses on classical road pollutants (NO_x and PM2.5) as well as on fuel consumption reduction and CO₂. Moreover, impact assessment has been applied, employing a common approach: Eco-Indicator (EI) 99. The ranking of different car replacement options revealed prolonged car use as the environmentally better option. As a consequence of the continuous use of the car representing 2000 average technology, the components ‘vehicle travel’ and ‘fuel chain’ show a 10% and 9% higher performance, respectively. This effect is compensated by savings in ‘car infrastructure’ (26%). Uncertainty analysis has been performed by additional model runs with different parameter settings. Despite the fact that a considerably prolonged car use scores best for all additional model runs, the resulting differences between options further decrease. This holds particularly true, if a higher yearly average fuel reduction rate of 3% is assumed. Furthermore, applying an avoided burden concept for infrastructure modeling (Value Corrected Substitution (VCS)) shows the same effect. In both cases the resulting scores differ merely marginally between the considered options and would not allow for discrimination.As a consequence of these outcomes, it is not possible to give any general recommendation to Swiss car owners to extend the use of their cars, in the short term.