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PHEVs emit almost five times more planet-heating pollution than lab-reported data show, as per a recent report.

Widening Gap In Lab and Actual Emissions

Statistics reveals that PHEVs release just 19% less CO₂ than conventional petrol and diesel cars, based on research conducted by a non-profit group. This differs sharply with lab tests, which assumed a 75% reduction in emissions.

Analysts examined information from in-vehicle energy use monitors of eight hundred thousand vehicles sold in the EU between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, increased from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported figures are falling,” said a senior researcher participating in the report. “That gap is growing and poses a serious issue. Consequently, PHEVs pollute nearly as heavily as petrol vehicles.”

Key Reasons Driving the Discrepancy

Researchers linked the majority of the difference to overestimates of the “electric driving share” – the percentage of miles travelled in battery power compared to total distance. The team found that only 27% of driving was done in EV mode, while lab estimates suggested over four-fifths.

Even, when running in EV mode, emission levels were significantly higher than lab projections. This happened because electric motors were insufficiently powerful enough to function independently, resulting to combustion motors burning gasoline for almost one-third of the travel covered in EV mode.

Regulatory and Financial Consequences

According to calculations, the lowballing of PHEV emissions enabled several major carmaker groups to escape over €5bn in fines from 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO₂ standards.

Furthermore, owners of PHEVs would pay approximately €500 more per year in running expenses than would be estimated under lab tests.

“The strong claims that manufacturers often promote about their plug-in hybrid vehicles are obviously far from the mark,” stated a automotive expert. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are only slightly improved than standard gas and diesel cars in terms of fuel consumption, CO₂ production, and running expenses.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid cars have recently been drawn again into political discussions as carmakers have lobbied the EU to relax CO₂ standards. A planned ban on new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with significant car manufacturing.

Some high-level politicians have suggested PHEVs as a possible “compromise” option to introduce in the regulation.

One external energy economics specialist, who was unaffiliated with the research, described the analysis a “highly valuable contribution” after a long period in which parts of the automotive industry claimed there was too little data to accurately assess actual CO2 output.

“The results show, beyond any doubt, that the difference in lab and real-world PHEV energy use and CO₂ output is much, much greater than for petrol or conventional vehicles,” the expert said. “All policy adjustments concerning PHEVs should be implemented with utmost caution and in the light of this data.”