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PHEVs release almost five times greater global warming emissions than lab-reported data indicate, according to a new analysis.

Widening Discrepancy In Lab and Actual Emissions

Statistics shows that PHEVs release just 19% lower CO₂ than traditional petrol and diesel cars, based on analysis carried out by a non-profit organization. That differs significantly with laboratory tests, which assumed a 75% decrease in emissions.

Analysts examined information from onboard energy use meters of 800,000 cars sold in Europe between 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, increased from three and a half times in 2021.

“Actual emissions are rising, while lab-reported emissions are decreasing,” said a senior analyst involved in the report. “That discrepancy is growing and creates a serious problem. Consequently, PHEVs emit almost as heavily as gasoline cars.”

Primary Reasons Behind the Emissions Gap

Analysts linked the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers driven in battery mode relative to overall mileage. The team found that only a quarter of driving was completed in electric mode, while lab assumptions suggested 84%.

Additionally, when running in EV mode, emission levels were significantly higher than lab estimates. This occurred because EV motors were not strong sufficient to function independently, resulting to combustion motors burning gasoline for nearly one-third of the travel completed in electric mode.

Regulatory and Financial Implications

Based on calculations, the lowballing of PHEV emissions enabled four major carmaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs would spend approximately €500 extra per year in running costs than would be assumed under lab tests.

“The strong claims that manufacturers often promote about their PHEV vehicles are obviously far from the mark,” stated a transport analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly better than standard petrol and diesel cars in terms of energy consumption, CO₂ emissions, and operating costs.”

Policy Debate and Industry Pressure

Hybrid vehicles have lately been drawn again into policy debates as carmakers have lobbied the EU to relax CO₂ standards. A planned ban on new internal combustion cars in 2035 has faced intense pressure from the car industry and resistance from EU countries with significant automotive industries.

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

An external energy policy specialist, who was not involved with the study, called the report a “highly valuable addition” after a long period in which parts of the car industry argued there was too little data to accurately assess real-world CO2 output.

“The results show, beyond any doubt, that the difference in official and actual PHEV energy use and CO₂ emissions is significantly greater than for petrol or diesel vehicles,” the expert stated. “Any regulatory changes concerning PHEVs should be implemented with extreme care and in the light of this evidence.”