A study conducted by Hayato Goto et al., in collaboration with Toyota Motor Corporation, was published in the Transportation Research Part D: Transport and Environment.
Plug-in hybrid electric vehicles (PHEVs) represent another practical option for reducing CO₂ emissions on the road, by alleviating range anxiety and reducing the use of critical minerals in batteries. However, the effect depends on the electric mileage ratio (EMR). This study explored the relationship between EMRs and charging habits, traffic conditions, driver disposition, socioeconomic attributes, and area characteristics by analyzing the vehicle log data from 6,190 PHEVs across 22 Japanese cities using an Explainable Boosting Machine (EBM), which provides higher prediction accuracy and clearer interpretability than traditional methods.
Our analysis revealed that charging habits and driver disposition had a greater impact on the EMR compared with other factors. We also found that encouraging home charging could be more effective in improving the EMR than developing public charging stations by promoting policies based on the learned EBM. Our results provide useful information for developing policies to improve the on-road CO₂ emission reduction benefits of PHEVs.
Title: How to Improve PHEV Electric Mileage Ratios? Factor Decomposition with Explainable
Authors: Goto, H., Nishi, T., Shiga, T., Sasai, T., Fukushima, S.
Journal Name: Transportation Research Part D: Transport and Environment
Published: September 1, 2025