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Plug-in hybrid cars produce almost five times more global warming pollution than lab-reported figures indicate, as per a recent report.

Growing Gap Between Lab and Actual CO2 Output

Data shows that PHEVs release just 19% lower CO₂ than traditional gas and diesel cars, according to research conducted by a non-profit group. This contrasts sharply with lab tests, which assumed a three-quarters decrease in emissions.

Researchers studied information from onboard energy use monitors of eight hundred thousand cars sold in the EU between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while official figures are decreasing,” stated a senior analyst involved in the report. “That discrepancy is widening and poses a serious issue. As a result, PHEVs pollute almost as heavily as petrol vehicles.”

Primary Factors Driving the Discrepancy

Researchers attributed the majority of the difference to inflated estimates of the “utility factor” – the percentage of kilometers driven in electric mode relative to total mileage. The team found that just 27% of travel was done in electric mode, while lab assumptions assumed over four-fifths.

Even, when operating in electric mode, emission levels were well above lab projections. That happened because EV motors were insufficiently powerful sufficient to function independently, leading to engines burning gasoline for nearly one-third of the distance covered in EV mode.

Policy and Financial Consequences

According to calculations, the underestimation of PHEV emissions enabled four large automaker companies to avoid more than €5bn in fines from 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would spend about €500 extra per year in running costs than would be estimated under laboratory conditions.

“The bold claims that automakers often promote about their plug-in hybrid vehicles are obviously way off the truth,” stated a automotive analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of fuel consumption, CO₂ production, and running expenses.”

Policy Discussion and Automotive Lobbying

Hybrid cars have recently been drawn back into political discussions as carmakers have pressed the EU to relax CO₂ targets. A proposed ban on new combustion engine cars in 2035 has faced intense lobbying from the automotive industry and resistance from EU countries with large automotive industries.

Some senior politicians have proposed PHEVs as a potential “compromise” option to include in the legislation.

An external energy policy specialist, who was unaffiliated with the study, described the analysis a “very useful addition” after years in which parts of the automotive sector argued there was insufficient information to accurately evaluate actual emissions.

“These findings show, beyond any doubt, that the difference in official and real-world PHEV energy use and CO₂ output is much, much greater than for petrol or conventional vehicles,” the expert said. “Any policy adjustments regarding PHEVs should be implemented with utmost care and in the light of that evidence.”