Low Emission Zones have been designed to address health issues. Their implementation will have the effect of accelerating the replacement of old thermal vehicles by more recent or electric vehicles. Is an early conversion of the fleet under this scheme or under "social lease" type measures relevant from the point of view of greenhouse gas emissions? If we take into account the impacts linked to production, should we not on the contrary seek to make the existing thermal vehicles last as long as possible? This Issue Brief examines the stakes of an issue that is often put forward in debates to question the relevance of Low Emission Zones or the electrification of vehicles.

Key Messages

  • Extending the lifespan of a thermal vehicle only marginally reduces greenhouse gas emissions per additional kilometre travelled, as the use of fossil fuel (the unavoidable part of emissions) accounts for more than 70% of the impact over the entire life cycle of these products.
  • Extending the lifespan of an electric vehicle is an important lever for reducing greenhouse gas emissions. Encouraging long lifetimes for this type of motorisation must be the focus of a proactive public policy (the regulation on the durability of batteries currently under discussion at European level is a priority in this respect).
  • For an owner wishing to choose a more virtuous alternative when replacing his vehicle, the scenario that proves to be the least greenhouse gas emitting consists in replacing his thermal vehicle by an electric vehicle in advance (taking into account both the impact of the vehicle's manufacturing process and the fact that the thermal vehicle could have been used for an additional 4 years).
  • Extending the lifespan of a thermal vehicle can only be considered for people who do not use their vehicle very often and on the condition that they switch to an electric vehicle when the vehicle is eventually renewed. Buying a new, more fuel-efficient thermal vehicle to replace an old one and then keeping it for 18 years (the average lifespan of vehicles in France) has the worst greenhouse gas emissions record.
  • These elements linked to global warming issues could be completed by studying other environmental indicators: depletion of mineral resources, impacts associated with mining activities, water consumption, etc. Furthermore, the modelled scenarios deliberately do not question the demand for transport, nor the size or efficiency of vehicles, even though all these elements must be mobilised and are undoubtedly intrinsic conditions for the success of the transition.
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