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PHEVs produce nearly five times more planet-heating emissions than official data indicate, as per a new report.

Widening Discrepancy In Lab and Real-World Emissions

Data reveals that PHEVs release just one-fifth lower CO₂ than conventional gas and diesel cars, according to analysis conducted by a non-profit group. This contrasts significantly with laboratory estimates, which assumed a three-quarters decrease in pollution.

Researchers examined data from onboard energy use monitors of eight hundred thousand cars sold in the EU from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, up from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported figures are falling,” stated a senior analyst participating in the report. “This discrepancy is widening and creates a significant problem. Consequently, PHEVs pollute almost as heavily as petrol cars.”

Key Reasons Driving the Discrepancy

Analysts linked most of the gap to inflated estimates of the “electric driving share” – the ratio of miles driven in electric power relative to overall distance. The team found that only a quarter of travel was done in electric mode, whereas official assumptions suggested over four-fifths.

Additionally, when operating in electric mode, emission levels were well above lab projections. That happened because EV motors were not strong sufficient to operate independently, leading to engines burning fossil fuels for nearly one-third of the distance covered in EV mode.

Regulatory and Financial Consequences

Based on estimates, the lowballing of PHEV emissions enabled several large carmaker groups to avoid over €5bn in fines from 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ targets.

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

“The strong statements that manufacturers often promote about their plug-in hybrid vehicles are clearly far from the truth,” commented a automotive analyst. “Consumers are being duped into believing that by buying a PHEV, they are helping the planet and saving costs. Actually, PHEVs are only slightly improved than standard gas and diesel cars in terms of fuel use, CO₂ production, and running expenses.”

Political Debate and Industry Pressure

Hybrid cars have lately been drawn again into political debates as automakers have pressed the European Union to relax CO₂ standards. A planned ban on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the car industry and resistance from EU countries with significant car manufacturing.

Some senior officials have suggested PHEVs as a potential “flexibility” solution to include in the regulation.

One external energy economics specialist, who was not involved with the research, called the report a “highly valuable contribution” after years in which parts of the automotive sector argued there was insufficient data to accurately assess actual CO2 output.

“The results demonstrate, without question, that the difference in official and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or diesel cars,” the expert said. “Any policy changes concerning PHEVs should be made with utmost care and considering that evidence.”