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PHEVs release nearly five times greater global warming pollution than official data show, according to a new analysis.

Widening Gap Between Lab and Actual CO2 Output

Data shows that PHEVs release only one-fifth less CO₂ than conventional petrol and diesel cars, based on research carried out by a non-profit group. This differs significantly with lab tests, which assumed a three-quarters decrease in pollution.

Analysts examined data from in-vehicle fuel consumption monitors of eight hundred thousand cars registered in Europe from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are falling,” stated a senior researcher participating in the report. “This discrepancy is growing and creates a significant issue. Consequently, PHEVs pollute almost as heavily as gasoline cars.”

Primary Factors Behind the Discrepancy

Researchers attributed most of the gap to inflated estimates of the “utility factor” – the percentage of kilometers travelled in battery mode relative to total mileage. The team found that just 27% of driving was done in EV mode, whereas lab assumptions suggested over four-fifths.

Even, when running in electric mode, emission levels were significantly higher than lab estimates. That happened because electric motors were not strong enough to function alone, resulting to combustion motors burning fossil fuels for almost a third of the travel completed in electric mode.

Regulatory and Economic Implications

Based on calculations, the underestimation of PHEV emissions enabled several major automaker groups to escape over €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs would spend about €500 more per year in operating expenses than would be assumed under lab tests.

“The bold claims that automakers often promote about their plug-in hybrid cars are clearly way off the truth,” commented a automotive expert. “Consumers are being duped into believing that by buying a PHEV, they are helping the planet and cutting money. Actually, PHEVs are little better than standard gas and diesel cars in terms of fuel use, CO₂ emissions, and running costs.”

Political Discussion and Industry Lobbying

Hybrid cars have lately been drawn again into political discussions as carmakers have pressed the European Union to relax CO₂ standards. A proposed ban on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with significant car manufacturing.

Several senior politicians have proposed PHEVs as a potential “compromise” solution to introduce in the legislation.

An independent energy policy specialist, who was unaffiliated with the study, described the report a “highly valuable contribution” after years in which segments of the automotive sector claimed there was insufficient information to properly assess real-world emissions.

“The results show, beyond any doubt, that the gap in official and actual PHEV energy use and CO₂ output is much, much greater than for petrol or diesel vehicles,” the expert said. “Any regulatory changes concerning PHEVs should be made with utmost care and in the light of that data.”