White paper

Real world usage of plug-in hybrid vehicles in the United States

This study examines the current state of PHEV usage in the United States using recent data from two previously unexplored sources: self-reported fuel consumption from Fuelly.com and engine-off distance traveled collected by the California Bureau of Automotive Repair (BAR).

The analysis of the new datasets presents strong evidence that real-world electric drive share is far below the utility factor label rating. Specifically, the analysis finds that real-world electric drive share may be 26%–56% lower and real-world fuel consumption may be 42%–67% higher than assumed within EPA’s labeling program for light duty vehicles.

More data collection could provide greater precision and clarity regarding the deviation of real-world electric drive share and what is assumed in EPA labeling. As PHEVs are still a small share of the existing fleet and new sales, all data sources to date may be inherently biased towards early adopters. In addition, all datasets examined suffer from some degree of self-selection bias, and potentially other confounding factors. At a minimum, the trends in the new PHEV data point to the need for closer inspection and broader investigation into PHEV usage to inform regulatory treatment.