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PHEVs emit nearly 5x greater planet-heating pollution than lab-reported data show, as per a new report.

Widening Gap Between Lab and Real-World CO2 Output

Statistics shows that PHEVs release just 19% lower CO₂ than traditional gas and diesel cars, based on analysis carried out by a non-profit organization. That contrasts sharply with laboratory estimates, which suggested a 75% decrease in emissions.

Analysts examined information from onboard energy use meters of eight hundred thousand cars registered in Europe from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while official emissions are decreasing,” said a senior analyst participating in the report. “This discrepancy is widening and poses a significant issue. As a result, PHEVs emit nearly as much as petrol vehicles.”

Key Reasons Behind the Emissions Gap

Researchers attributed the majority of the difference to overestimates of the “utility factor” – the percentage of miles travelled in battery power compared to total mileage. The team determined that just a quarter of driving was completed in EV mode, while lab estimates assumed over four-fifths.

Even, when operating in EV mode, emission amounts were well above lab projections. This happened because electric motors were not strong enough to function alone, resulting to combustion motors burning gasoline for almost a third of the travel completed in EV mode.

Regulatory and Economic Consequences

According to calculations, the underestimation of PHEV emissions enabled four major carmaker companies to escape over €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ standards.

Furthermore, owners of PHEVs would spend approximately €500 more per year in operating costs than is estimated under laboratory tests.

“The bold claims that automakers often promote about their plug-in hybrid cars are clearly far from the mark,” stated a transport analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the environment and cutting money. Actually, PHEVs are little improved than standard gas and diesel vehicles in terms of fuel use, CO₂ production, and operating expenses.”

Political Debate and Industry Pressure

Hybrid vehicles have recently been brought back into policy discussions as carmakers have lobbied the European Union to weaken CO₂ targets. A proposed prohibition on sales of new combustion engine cars in 2035 has faced heavy lobbying from the automotive sector and opposition from EU countries with large car manufacturing.

Several high-level officials have proposed PHEVs as a potential “flexibility” option to introduce in the legislation.

An external energy economics expert, who was not involved with the study, called the analysis a “highly valuable addition” after years in which segments of the car sector claimed there was insufficient data to accurately assess actual CO2 output.

“The results show, without question, that the difference between official and real-world PHEV energy use and CO₂ output is significantly larger than for petrol or conventional cars,” the expert said. “All policy adjustments concerning PHEVs should be implemented with utmost care and considering this evidence.”