ICCT | Highlighted on Fuelcons
The actual impact of plug-in hybrid and battery electric vehicles (PHEV and BEV) on greenhouse gas (GHG) mitigation depends on their real-world usage. PHEVs, with their smaller batteries compared to BEVs, which implies lower emissions during vehicle production, can contribute to GHG emission reduction. However, their overall environmental impact hinges on efficient operation and the Utility Factor (UF), quantifying the electric distance fraction. Accordingly, fuel consumption and CO2 emissions of PHEVs are correlated with operating environments (e.g. private vs. company cars) and charging frequency. Two white papers from the International Council on Clean Transportation (ICCT) recently delved into PHEV real-world usage in Europe and the US, addressing the divergence between real-world and type-approval (WLTP/EPA) fuel consumption.
The first paper focuses on PHEV performance in Europe, particularly those certified under the Worldwide Harmonized Light Vehicles Test Procedure (WLTP). It reveals substantial disparities between real-world PHEV performance and WLTP type-approval values. Real-world fuel consumption in Europe averages three to five times higher than WLTP-certified figures, with private vehicles at 4.0–4.4 L/100 km and company cars at 7.6–8.4 L/100 km compared to the 1.6–1.7 L/100 km in WLTP type-approval. This translates to significantly higher tailpipe emissions, ranging from 90–105 g CO2/km for private vehicles and 175–195 g CO2/km for company cars, compared to the 37–39 g CO2/km in WLTP type-approval. Moreover, a growing gap between real-world and type-approval fuel consumption has been observed since 2012, equating to an average annual increase of 0.1–0.2 L/100 km.
The second paper explores PHEV performance in the United States, assessing their potential to reduce emissions and fossil fuel consumption. It analyzes recent data from two sources: self-reported fuel consumption on Fuelly.com and engine-off distance traveled data collected by the California Bureau of Automotive Repair (BAR). These datasets encompass a wide range of PHEV models, offering a comprehensive view of their performance in the US. The analysis indicates that real-world electric drive share (or UF) in PHEVs may be significantly lower (26%–56% lower) than assumed within the EPA’s labeling program for light-duty vehicles. Consequently, real-world fuel consumption could be considerably higher (42%–67% higher) than EPA label figures, challenging assumptions made in EPA labeling regarding PHEV performance. This emphasizes the need for a more precise representation of PHEV performance to effectively reduce emissions and fuel consumption in real-world driving conditions.
Sources:
ICCT White Paper | Plötz et al. (2022): Real-world usage of plug-in hybrid vehicles in Europe: A 2022 update on fuel consumption, electric driving, and CO2 emissions
ICCT White Paper | Isenstadt et al. (2022) | Real world usage of plug-in hybrid vehicles in the United States