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Plug-in hybrid electric vehicles emit almost 5x more global warming emissions than lab-reported figures show, as per a recent analysis.

Widening Gap Between Official and Real-World Emissions

Data reveals that PHEVs release just 19% less CO₂ than traditional gas and diesel cars, according to analysis carried out by a non-profit organization. This contrasts sharply with laboratory estimates, which assumed a three-quarters decrease in emissions.

Researchers examined data from in-vehicle fuel consumption meters of eight hundred thousand vehicles sold in the EU between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, up from three and a half times in 2021.

“Actual emissions are increasing, while official figures are decreasing,” said a senior analyst participating in the study. “That gap is widening and poses a serious issue. Consequently, PHEVs pollute nearly as much as gasoline cars.”

Key Reasons Behind the Discrepancy

Researchers linked the majority of the gap to inflated estimates of the “electric driving share” – the ratio of miles driven in battery power compared to overall mileage. The team determined that only 27% of driving was completed in electric mode, whereas official assumptions assumed over four-fifths.

Even, when operating in EV mode, pollution levels were well above official estimates. This occurred because electric motors were not strong sufficient to operate alone, leading to combustion motors using gasoline for nearly one-third of the travel completed in EV mode.

Regulatory and Economic Implications

Based on calculations, the underestimation of PHEV emissions allowed four large automaker groups to escape more than €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would spend about €500 more per year in running expenses than is assumed under laboratory conditions.

“The strong claims that automakers like to make about their PHEV cars are clearly far from the truth,” commented a automotive expert. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the planet and saving money. Actually, PHEVs are only slightly improved than regular petrol and diesel cars in terms of fuel use, CO₂ emissions, and running expenses.”

Policy Discussion and Industry Pressure

Hybrid cars have recently been drawn again into political debates as automakers have pressed the EU to relax CO₂ targets. A proposed prohibition on new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and resistance from EU countries with large car manufacturing.

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

An external energy economics expert, who was not involved with the research, described the analysis a “highly valuable contribution” after years in which parts of the car sector argued there was insufficient information to accurately evaluate actual emissions.

“The results demonstrate, without question, that the gap between official and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or diesel vehicles,” the expert stated. “Any regulatory adjustments regarding PHEVs should be made with extreme caution and considering that data.”