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PHEVs emit nearly five times more global warming emissions than lab-reported data indicate, according to a recent analysis.

Widening Discrepancy In Lab and Actual CO2 Output

Data shows that PHEVs release just one-fifth less CO₂ than traditional petrol and diesel cars, according to analysis carried out by a non-profit group. That differs sharply with laboratory estimates, which suggested a 75% decrease in pollution.

Analysts examined data from in-vehicle fuel consumption meters of eight hundred thousand vehicles registered in Europe from 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while official figures are decreasing,” said a senior analyst participating in the report. “That gap is widening and creates a significant issue. Consequently, PHEVs pollute nearly as much as gasoline vehicles.”

Key Factors Behind the Discrepancy

Analysts attributed the majority of the difference to overestimates of the “utility factor” – the ratio of miles travelled in battery mode relative to total mileage. The team found that only 27% of travel was done in electric mode, while lab estimates suggested over four-fifths.

Additionally, when running in electric mode, emission amounts were significantly higher than lab projections. That occurred because EV motors were not strong sufficient to function alone, resulting to engines burning gasoline for nearly one-third of the distance covered in EV mode.

Policy and Financial Consequences

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

Additionally, drivers of PHEVs would spend approximately €500 more per year in operating costs than is assumed under laboratory tests.

“The strong claims that automakers like to make about their PHEV vehicles are clearly far from the truth,” commented a automotive analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are helping the planet and saving costs. In reality, PHEVs are only slightly better than regular gas and diesel vehicles in terms of fuel use, CO₂ emissions, and running expenses.”

Policy Debate and Industry Pressure

Plug-in hybrid cars have lately been drawn back into political discussions as carmakers have lobbied the EU to relax CO₂ standards. A planned ban on sales of new internal combustion cars in 2035 has faced intense pressure from the car industry and opposition from EU countries with significant car industries.

Some high-level officials have suggested PHEVs as a potential “flexibility” option to include in the legislation.

One external energy policy specialist, who was unaffiliated with the research, described the report a “highly valuable addition” after years in which parts of the car industry argued there was too little information to accurately evaluate real-world CO2 output.

“The results show, without question, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or conventional cars,” the expert said. “Any policy adjustments regarding PHEVs should be made with utmost care and in the light of that evidence.”