Factors impacting real-world fuel economy of plug-in hybrid electric vehicles in Europe - an empirical analysis

Plug-in hybrid electric vehicles (PHEVs) combine an electric motor with an internal combustion engine and can reduce greenhouse gas emissions from transport if mainly driven on electricity. The environmental benefit of PHEVs strongly depends on its usage and charging behavior. Several studies have demonstrated low electric driving shares (EDS) of many PHEVs. However, there is limited evidence on which vehicle properties affect the EDS of PHEVs to which extent. Here, we provide an empirical and quantitative analysis of real-world EDS and fuel consumption and look at how they are impacted by factors related to vehicle properties such as range, system power and mass. We complement previous studies on real-world EDS and fuel consumption of PHEVs by combining two different data sets, with almost 100,000 vehicles in total, over 150 models in 41 countries, which is combined the largest PHEV sample in Europe to date to be analyzed in the literature. We find that an increase of 10 km of type approval range leads on average to 13%-17% fuel consumption decrease and 1%-4% EDS increase. Furthermore, a 1 kW increase in system power per 100 kg of vehicle mass is associated with an average increase of 7%-9% in fuel consumption and a decrease of up to 2% in EDS. We also find that long-distance driving and charging behavior are the largest non-technical factors for the deviation between type-approval and real-world data. Furthermore, PHEV fuel consumption and related tail-pipe emissions in Europe are on average higher than official EU values.