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PHEVs release nearly 5x more global warming emissions than lab-reported figures indicate, according to a new report.

Growing Discrepancy In Official and Actual Emissions

Statistics shows that PHEVs release only one-fifth lower CO₂ than traditional petrol and diesel cars, according to research conducted by a non-profit organization. That contrasts sharply with lab estimates, which suggested a three-quarters reduction in emissions.

Researchers studied information from onboard fuel consumption monitors of eight hundred thousand vehicles sold in the EU from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, up from three and a half times in 2021.

“Real-world CO2 output are rising, while official emissions are decreasing,” said a senior researcher participating in the study. “That discrepancy is widening and poses a significant issue. As a result, PHEVs emit nearly as much as gasoline cars.”

Key Reasons Driving the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in battery mode relative to overall mileage. The team determined that just 27% of travel was done in EV mode, while lab assumptions suggested over four-fifths.

Even, when operating in EV mode, pollution levels were well above lab estimates. That occurred because EV motors were not strong sufficient to function independently, leading to engines using gasoline for almost one-third of the distance covered in electric mode.

Policy and Financial Consequences

Based on calculations, the lowballing of PHEV emissions enabled several large automaker groups to avoid more than €5bn in fines from 2021 and 2023, by falsely simplifying adherence with EU average fleet CO₂ standards.

Additionally, owners of PHEVs could pay approximately €500 extra per year in running expenses than is estimated under lab conditions.

“The strong statements that manufacturers often promote about their PHEV vehicles are obviously way off the mark,” commented a automotive analyst. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy consumption, CO₂ emissions, and running expenses.”

Policy Debate and Industry Pressure

Hybrid vehicles have lately been drawn again into political debates as automakers have pressed the EU to weaken CO₂ targets. A planned prohibition on new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from EU countries with significant automotive industries.

Some senior officials have proposed PHEVs as a possible “flexibility” solution to introduce in the regulation.

One external energy policy expert, who was unaffiliated with the research, described the analysis a “very useful contribution” after years in which parts of the automotive sector claimed there was insufficient information to properly evaluate actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or diesel cars,” they said. “Any regulatory changes concerning PHEVs should be implemented with extreme care and considering that evidence.”