Comparing carbon performances of mobility services and private vehicles from a life cycle perspective

Mobility services are predicted to replace private passenger vehicles to sizeable shares in the short- and middle-term. Although the carbon saving potential of mobility services compared to private vehicles is widely acknowledged, empirical studies are lacking and research designs remain unreplicated. In order to determine common characteristics of studies comparing life cycle carbon emissions of mobility services and passenger vehicles, we conducted a standardized literature review. We showed that current Life Cycle Assessment (LCA)-based approaches in the research field mostly apply two methodological characteristics: (1) person-km (p-km) are used as reference unit to compare carbon performances across transport modes and (2) scenario-analyses are used to deal with the poor data basis and disruptive character of mobility services. Most studies focus on comparing conventionally-powered car sharing vehicles to passenger cars within a one year timeframe in urban areas. Mobility services like ride hailing and pooling as well as alternative power trains remain largely neglected. Policy-makers and customers were found to be the main addressees of case studies. The private sector is least addressed thus showing the need for future research on a mix of mobility services and private vehicles with different power trains on fleet level.