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Plug-in hybrid electric vehicles release almost five times more global warming emissions than lab-reported data show, as per a recent report.

Growing Gap Between Lab and Real-World CO2 Output

Statistics reveals that PHEVs emit only one-fifth less CO₂ than conventional gas and diesel cars, based on analysis conducted by a non-profit organization. That contrasts significantly with lab tests, which assumed a three-quarters reduction in pollution.

Analysts studied data from in-vehicle energy use monitors of 800,000 cars sold in the EU between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, up from three and a half times in 2021.

“Actual CO2 output are rising, while official figures are falling,” said a lead researcher participating in the study. “This discrepancy is widening and poses a serious problem. As a result, PHEVs emit almost as much as petrol vehicles.”

Primary Reasons Behind the Discrepancy

Researchers linked the majority of the gap to inflated estimates of the “utility factor” – the ratio of miles driven in battery power compared to overall mileage. They found that just 27% of travel was completed in EV mode, while lab assumptions assumed over four-fifths.

Additionally, when operating in EV mode, pollution amounts were well above lab estimates. That occurred because electric motors were insufficiently powerful enough to operate alone, leading to engines burning gasoline for almost one-third of the distance completed in EV mode.

Regulatory and Economic Implications

According to calculations, the lowballing of PHEV emissions enabled four large automaker groups to avoid over €5bn in penalties between 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs could pay approximately €500 more annually in operating expenses than is assumed under lab tests.

“The strong claims that manufacturers often promote about their PHEV cars are clearly far from the mark,” stated a transport expert. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel use, CO₂ production, and operating expenses.”

Political Discussion and Automotive Pressure

Plug-in hybrid vehicles have lately been drawn back into political discussions as automakers have pressed the EU to relax CO₂ targets. A proposed ban on new internal combustion vehicles in 2035 has faced heavy pressure from the car sector and opposition from EU countries with significant automotive manufacturing.

Several high-level politicians have proposed plug-in hybrids as a potential “compromise” solution to introduce in the regulation.

An external energy policy specialist, who was unaffiliated with the study, described the report a “highly valuable contribution” after years in which parts of the car industry claimed there was insufficient data to accurately assess real-world emissions.

“These findings demonstrate, without question, that the difference in lab and real-world PHEV fuel consumption and CO₂ output is much, much larger than for petrol or diesel vehicles,” they stated. “Any regulatory changes regarding PHEVs should be implemented with extreme caution and considering that data.”