A review of fleet-based life-cycle approaches focusing on energy and environmental impacts of vehicles

Fleet-based LC approaches have been applied with different purposes (e.g., to model recycling processes, to assess trade-offs between manufacturing and use impacts; to optimize product service life). The issue of evaluating the impacts of introducing alternative technologies is appropriately addressed by a fleet-based LC approach, because it allows for the capture of displacement effects, technological improvements over time, and changes in background processes. Several studies have used such an approach to assess scenarios of evolution of the light-duty fleet. The main key aspects are: fleet penetration rate, electricity source, fuel economy improvements, and vehicle weight reduction. Emission reductions were found to be very dependent on the underlying assumptions. Reducing fuel consumption is one of the key ways to reduce fleet GHG emissions, but it needs to be combined with other measures, such as high penetration of advanced technologies, to bring about significant reductions. The electricity generation source has also a large impact on the fleet GHG emissions and increasing renewable energy penetration is key to reduce overall emissions.