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PHEVs produce almost 5x more global warming pollution than official data show, according to a new analysis.

Growing Gap Between Official and Actual CO2 Output

Data reveals that PHEVs emit only one-fifth lower CO₂ than conventional petrol and diesel vehicles, according to analysis conducted by a advocacy organization. That differs significantly with laboratory estimates, which suggested a 75% reduction in emissions.

Researchers examined data from onboard energy use meters of 800,000 vehicles registered in Europe from 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official figures are falling,” stated a senior analyst involved in the study. “That gap is widening and poses a serious problem. As a result, PHEVs emit almost as much as gasoline cars.”

Key Reasons Driving the Discrepancy

Analysts linked the majority of the difference to overestimates of the “utility factor” – the ratio of kilometers driven in battery mode relative to overall mileage. The team determined that just 27% of driving was completed in EV mode, whereas official estimates suggested over four-fifths.

Even, when operating in EV mode, emission amounts were significantly higher than lab estimates. This happened because electric motors were insufficiently powerful enough to operate independently, resulting to combustion motors burning fossil fuels for nearly a third of the travel completed in EV mode.

Regulatory and Financial Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled several large carmaker companies to avoid over €5bn in fines between 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs would spend about €500 more annually in running costs than is estimated under laboratory conditions.

“The bold statements that automakers often promote about their plug-in hybrid vehicles are obviously far from the mark,” stated a automotive expert. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are only slightly better than standard petrol and diesel vehicles in terms of energy use, CO₂ emissions, and operating costs.”

Policy Debate and Industry Lobbying

Plug-in hybrid cars have recently been brought again into political discussions as automakers have pressed the EU to weaken CO₂ targets. A proposed ban on new internal combustion vehicles in 2035 has faced heavy lobbying from the car sector and resistance from member states with significant automotive industries.

Some high-level politicians have proposed plug-in hybrids as a possible “flexibility” option to include in the legislation.

An independent energy policy specialist, who was unaffiliated with the research, called the analysis a “highly valuable addition” after years in which segments of the automotive sector claimed there was insufficient data to properly assess actual emissions.

“These findings demonstrate, without question, that the gap in official and real-world PHEV energy use and CO₂ emissions is much, much larger than for petrol or conventional cars,” they said. “All policy changes regarding PHEVs should be implemented with utmost caution and considering this evidence.”