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Plug-in hybrid electric vehicles produce nearly 5x greater global warming pollution than official figures indicate, according to a new report.

Growing Discrepancy In Lab and Real-World Emissions

Data reveals that PHEVs emit just 19% less CO₂ than conventional gas and diesel cars, according to analysis conducted by a non-profit organization. This contrasts significantly with laboratory tests, which assumed a 75% reduction in emissions.

Analysts examined information from onboard energy use meters of eight hundred thousand vehicles sold in the EU from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while lab-reported emissions are decreasing,” stated a senior researcher involved in the study. “This gap is widening and poses a serious problem. As a result, PHEVs pollute almost as much as gasoline vehicles.”

Primary Reasons Driving the Emissions Gap

Researchers attributed most of the difference to overestimates of the “utility factor” – the percentage of kilometers travelled in battery mode compared to overall distance. They determined that only 27% of driving was completed in electric mode, whereas official assumptions suggested 84%.

Additionally, when running in EV mode, emission levels were well above lab estimates. This occurred because electric motors were insufficiently powerful sufficient to function independently, resulting to engines using fossil fuels for almost one-third of the travel covered in EV mode.

Policy and Economic Consequences

Based on estimates, the lowballing of PHEV CO2 output enabled four major carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ targets.

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

“The bold statements that manufacturers like to make about their PHEV vehicles are obviously far from the truth,” stated a automotive expert. “Buyers are being duped into believing that by buying a PHEV, they are helping the planet and saving money. In reality, PHEVs are little better than regular petrol and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Policy Debate and Industry Lobbying

Hybrid cars have lately been drawn back into political debates as carmakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on new combustion engine vehicles in 2035 has faced heavy pressure from the automotive industry and opposition from member states with large automotive manufacturing.

Some high-level officials have suggested plug-in hybrids as a possible “flexibility” solution to include in the legislation.

One external energy policy expert, who was unaffiliated with the research, called the report a “very useful addition” after years in which parts of the automotive industry argued there was too little data to properly evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the difference in official and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel vehicles,” they stated. “All policy adjustments regarding PHEVs should be made with extreme care and considering that evidence.”