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PHEVs emit nearly five times greater global warming pollution than lab-reported figures indicate, according to a new report.

Widening Discrepancy Between Lab and Actual Emissions

Statistics reveals that PHEVs emit just one-fifth lower CO₂ than traditional petrol and diesel cars, based on research conducted by a advocacy group. This differs sharply with laboratory estimates, which assumed a 75% decrease in emissions.

Researchers studied information from onboard energy use monitors of 800,000 cars registered in the EU between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are falling,” said a senior analyst participating in the study. “This discrepancy is widening and creates a significant problem. Consequently, PHEVs pollute nearly as much as gasoline vehicles.”

Primary Reasons Driving the Discrepancy

Analysts linked the majority of the difference to overestimates of the “electric driving share” – the percentage of miles driven in battery power compared to overall mileage. The team determined that only 27% of driving was done in electric mode, while official estimates assumed 84%.

Additionally, when operating in EV mode, emission amounts were significantly higher than official projections. This occurred because electric motors were not strong sufficient to function alone, resulting to combustion motors burning gasoline for almost one-third of the distance covered in electric mode.

Policy and Economic Implications

Based on estimates, the underestimation of PHEV CO2 output enabled four major carmaker groups to escape more than €5bn in fines between 2021 and 2023, by falsely simplifying adherence with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs would pay approximately €500 extra per year in running expenses than would be estimated under laboratory conditions.

“The strong claims that automakers often promote about their plug-in hybrid cars are obviously way off the truth,” commented a automotive expert. “Consumers are being duped into thinking that by buying a PHEV, they are helping the planet and saving money. Actually, PHEVs are little better than standard gas and diesel cars in terms of fuel consumption, CO₂ production, and running expenses.”

Political Discussion and Industry Pressure

Hybrid vehicles have lately been drawn back into political debates as carmakers have lobbied the EU to relax CO₂ standards. A planned prohibition on sales of new combustion engine cars in 2035 has faced heavy lobbying from the car sector and resistance from member states with large automotive manufacturing.

Some senior politicians have proposed plug-in hybrids as a possible “flexibility” solution to include in the legislation.

An external energy economics specialist, who was unaffiliated with the study, called the analysis a “highly valuable contribution” after years in which parts of the automotive sector argued there was insufficient data to accurately assess real-world CO2 output.

“The results demonstrate, without question, that the gap in official and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or conventional cars,” they stated. “Any regulatory changes concerning PHEVs should be made with extreme caution and considering this evidence.”