Plug-in Hybrid Vehicles Pollute Nearly as Much as Gasoline Vehicles, Report Finds

Plug-in hybrid electric vehicles emit almost 5x greater global warming emissions than lab-reported data indicate, as per a new report.

Growing Discrepancy In Lab and Real-World CO2 Output

Data shows that PHEVs emit just 19% lower CO₂ than traditional gas and diesel vehicles, based on research carried out by a advocacy organization. That contrasts significantly with lab estimates, which assumed a three-quarters decrease in emissions.

Analysts examined information from in-vehicle energy use meters of eight hundred thousand cars sold in the EU from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official figures, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are decreasing,” said a senior researcher participating in the report. “This discrepancy is growing and creates a significant problem. Consequently, PHEVs pollute almost as heavily as petrol vehicles.”

Primary Factors Behind the Discrepancy

Analysts attributed the majority of the gap to inflated estimates of the “utility factor” – the percentage of miles driven in battery power relative to total distance. The team determined that only a quarter of travel was done in EV mode, while lab assumptions assumed over four-fifths.

Additionally, when running in electric mode, pollution levels were significantly higher than official projections. That happened because electric motors were not strong enough to operate independently, leading to combustion motors burning gasoline for nearly a third of the travel covered in electric mode.

Policy and Economic Consequences

Based on estimates, the underestimation of PHEV emissions allowed four major automaker companies to avoid over €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs would pay about €500 more annually in running costs than is assumed under lab conditions.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are clearly way off the truth,” stated a automotive expert. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are only slightly improved than standard petrol and diesel cars in terms of energy consumption, CO₂ emissions, and running costs.”

Policy Debate and Automotive Pressure

Hybrid cars have lately been drawn back into political discussions as carmakers have lobbied the European Union to weaken CO₂ targets. A planned prohibition on sales of new combustion engine cars in 2035 has faced intense pressure from the car industry and resistance from member states with significant automotive manufacturing.

Some senior politicians have proposed PHEVs as a potential “flexibility” option to introduce in the legislation.

One independent energy policy specialist, who was not involved with the research, described the analysis a “very useful contribution” after years in which parts of the automotive sector argued there was too little data to properly evaluate real-world emissions.

“These findings demonstrate, beyond any doubt, that the difference in lab and actual PHEV energy use and CO₂ output is much, much greater than for gasoline or conventional cars,” they said. “Any regulatory changes regarding PHEVs should be implemented with extreme care and considering that evidence.”