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PHEVs release nearly 5x greater planet-heating pollution than official data indicate, according to a recent report.

Growing Gap In Lab and Real-World Emissions

Statistics reveals that PHEVs emit only 19% lower CO₂ than traditional petrol and diesel cars, based on research conducted by a non-profit organization. That differs sharply with laboratory tests, which suggested a three-quarters decrease in emissions.

Analysts studied data from onboard fuel consumption meters of 800,000 cars sold in the EU between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are decreasing,” stated a senior analyst involved in the study. “That discrepancy is growing and creates a significant issue. Consequently, PHEVs emit almost as much as gasoline cars.”

Key Reasons Driving the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “utility factor” – the percentage of kilometers driven in electric mode relative to total mileage. The team found that only 27% of travel was done in EV mode, while lab assumptions assumed 84%.

Additionally, when running in EV mode, emission amounts were significantly higher than lab estimates. This happened because electric motors were insufficiently powerful sufficient to function independently, resulting to combustion motors burning gasoline for almost a third of the distance covered in electric mode.

Regulatory and Financial Consequences

Based on calculations, the lowballing of PHEV CO2 output allowed several large carmaker groups to avoid over €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs would spend about €500 more per year in running costs than would be assumed under lab tests.

“The bold claims that automakers often promote about their plug-in hybrid vehicles are obviously way off the mark,” stated a transport analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and running costs.”

Policy Debate and Automotive Pressure

Plug-in hybrid cars have lately been drawn back into policy debates as automakers have lobbied the EU to weaken CO₂ standards. A proposed ban on sales of new combustion engine cars in 2035 has faced heavy lobbying from the car sector and resistance from member states with significant automotive manufacturing.

Several high-level politicians have suggested PHEVs as a possible “compromise” solution to include in the regulation.

An independent energy economics specialist, who was unaffiliated with the research, described the report a “highly valuable contribution” after years in which segments of the car industry argued there was too little information to properly evaluate actual CO2 output.

“These findings demonstrate, without question, that the gap in official and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or diesel cars,” they stated. “All regulatory adjustments regarding PHEVs should be implemented with extreme care and in the light of that evidence.”