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Plug-in hybrid electric vehicles emit nearly 5x more planet-heating emissions than lab-reported figures indicate, according to a recent report.

Widening Gap In Lab and Actual CO2 Output

Data shows that PHEVs release just one-fifth lower CO₂ than traditional gas and diesel vehicles, based on analysis conducted by a non-profit organization. This differs significantly with laboratory tests, which assumed a 75% reduction in pollution.

Analysts examined data from onboard energy use monitors of 800,000 vehicles sold in the EU between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are decreasing,” said a senior analyst participating in the report. “That gap is widening and poses a significant problem. As a result, PHEVs pollute nearly as much as petrol cars.”

Key Factors Behind the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “utility factor” – the percentage of miles travelled in electric power compared to total mileage. They determined that only a quarter of travel was done in EV mode, while official assumptions suggested over four-fifths.

Even, when running in EV mode, emission levels were significantly higher than lab projections. This occurred because electric motors were insufficiently powerful enough to function independently, leading to engines burning gasoline for nearly a third of the travel completed in electric mode.

Policy and Economic Consequences

Based on estimates, the lowballing of PHEV emissions allowed several major automaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ targets.

Furthermore, owners of PHEVs would spend about €500 more annually in operating costs than would be assumed under laboratory conditions.

“The bold claims that automakers often promote about their PHEV vehicles are clearly far from the mark,” stated a automotive analyst. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are only slightly improved than regular gas and diesel cars in terms of fuel consumption, CO₂ production, and running costs.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have lately been drawn back into political discussions as automakers have pressed the European Union to weaken CO₂ targets. A proposed prohibition on new internal combustion cars in 2035 has faced intense pressure from the car industry and opposition from EU countries with significant automotive industries.

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

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

“These findings demonstrate, beyond any doubt, that the difference between official and real-world PHEV energy use and CO₂ output is much, much greater than for petrol or diesel vehicles,” they stated. “All regulatory changes regarding PHEVs should be made with utmost care and considering this evidence.”