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Plug-in hybrid cars emit nearly five times greater planet-heating emissions than official data show, as per a recent report.

Widening Gap In Lab and Real-World Emissions

Data shows that PHEVs release only 19% less CO₂ than traditional petrol and diesel vehicles, according to research carried out by a non-profit organization. That differs significantly with lab estimates, which assumed a three-quarters reduction in emissions.

Analysts studied information from onboard energy use meters of 800,000 vehicles registered in the EU from 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, up from three and a half times in 2021.

“Real-world CO2 output are rising, while official figures are decreasing,” stated a senior analyst involved in the study. “That discrepancy is widening and creates a significant issue. Consequently, PHEVs pollute almost as heavily as gasoline cars.”

Key Reasons Behind the Emissions Gap

Researchers attributed the majority of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in battery power relative to overall mileage. The team found that only 27% of driving was done in EV mode, whereas lab estimates assumed 84%.

Additionally, when running in electric mode, emission levels were well above official projections. This happened because EV motors were not strong enough to function alone, resulting to combustion motors using gasoline for almost one-third of the distance completed in EV mode.

Regulatory and Economic Implications

Based on estimates, the underestimation of PHEV CO2 output allowed four large automaker groups to escape more than €5bn in penalties from 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs could pay approximately €500 extra per year in running expenses than would be estimated under lab tests.

“The strong claims that automakers like to make about their plug-in hybrid cars are clearly way off the truth,” stated a automotive expert. “Consumers are being misled into believing that by buying a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are only slightly better than regular gas and diesel cars in terms of fuel use, CO₂ production, and running costs.”

Political Debate and Automotive Lobbying

Hybrid cars have lately been brought back into policy debates as automakers have lobbied the EU to weaken CO₂ targets. A planned prohibition on new internal combustion cars in 2035 has faced intense pressure from the automotive industry and opposition from member states with significant car manufacturing.

Some high-level officials have proposed PHEVs as a potential “compromise” solution to introduce in the regulation.

An independent energy economics specialist, who was unaffiliated with the research, described the report a “very useful contribution” after a long period in which segments of the automotive industry argued there was insufficient data to accurately evaluate real-world emissions.

“These findings demonstrate, without question, that the difference between official and real-world PHEV fuel consumption and CO₂ output is significantly larger than for petrol or diesel cars,” they said. “Any policy adjustments regarding PHEVs should be made with utmost caution and in the light of this evidence.”