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Plug-in hybrid electric vehicles produce almost five times more planet-heating pollution than lab-reported data indicate, as per a new report.

Growing Gap Between Lab and Actual CO2 Output

Statistics shows that PHEVs release only one-fifth lower CO₂ than conventional petrol and diesel cars, according to analysis conducted by a non-profit organization. This contrasts significantly with laboratory tests, which assumed a 75% reduction in pollution.

Analysts examined information from onboard fuel consumption monitors of eight hundred thousand vehicles sold in Europe between 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, up from 3.5 times in 2021.

“Actual CO2 output are rising, while official figures are decreasing,” stated a lead researcher participating in the study. “This gap is growing and poses a serious issue. As a result, PHEVs pollute almost as much as petrol vehicles.”

Key Factors Behind the Discrepancy

Researchers attributed most of the difference to overestimates of the “electric driving share” – the ratio of kilometers driven in battery power compared to overall distance. The team found that only 27% of travel was done in electric mode, whereas lab estimates suggested over four-fifths.

Additionally, when running in EV mode, pollution levels were significantly higher than official estimates. This happened because EV motors were not strong sufficient to operate alone, resulting to combustion motors using fossil fuels for almost a third of the distance covered in EV mode.

Regulatory and Financial Consequences

According to calculations, the lowballing of PHEV emissions allowed four major automaker groups to escape over €5bn in penalties from 2021 and 2023, by artificially easing adherence with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs could pay about €500 extra per year in operating expenses than is estimated under lab conditions.

“The bold statements that automakers often promote about their PHEV vehicles are clearly far from the mark,” commented a automotive analyst. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are only slightly better than standard petrol and diesel vehicles in terms of fuel use, CO₂ production, and operating costs.”

Policy Debate and Industry Pressure

Hybrid cars have lately been brought again into policy discussions as automakers have lobbied the European Union to weaken CO₂ standards. A planned ban on new internal combustion vehicles in 2035 has faced intense lobbying from the automotive sector and opposition from EU countries with significant car industries.

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

One external energy economics expert, who was not involved with the research, described the report a “highly valuable contribution” after years in which parts of the automotive sector claimed there was too little information to accurately evaluate real-world emissions.

“These findings demonstrate, without question, that the gap between official and real-world PHEV energy use and CO₂ output is significantly greater than for gasoline or conventional cars,” they said. “All policy adjustments regarding PHEVs should be made with extreme caution and considering this evidence.”