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Plug-in hybrid cars produce nearly 5x greater global warming pollution than lab-reported data indicate, according to a recent report.

Growing Gap In Official and Real-World CO2 Output

Data shows that PHEVs release just 19% less CO₂ than traditional gas and diesel vehicles, according to analysis conducted by a advocacy organization. That contrasts significantly with lab tests, which assumed a 75% reduction in emissions.

Researchers examined information from in-vehicle energy use monitors of 800,000 vehicles sold in Europe between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are decreasing,” stated a lead researcher involved in the study. “This gap is growing and poses a significant problem. Consequently, PHEVs pollute nearly as heavily as gasoline vehicles.”

Key Reasons Behind the Discrepancy

Analysts attributed the majority of the difference to overestimates of the “electric driving share” – the percentage of miles driven in battery power relative to overall mileage. They determined that just 27% of travel was done in electric mode, whereas lab estimates assumed 84%.

Even, when operating in electric mode, emission levels were significantly higher than lab estimates. That occurred because EV motors were insufficiently powerful sufficient to operate alone, resulting to engines burning fossil fuels for almost a third of the distance completed in EV mode.

Regulatory and Economic Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled several large automaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs could spend approximately €500 more per year in running expenses than would be assumed under lab tests.

“The strong statements that manufacturers often promote about their plug-in hybrid cars are obviously way off the mark,” stated a transport analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are little better than regular petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and running expenses.”

Political Debate and Industry Pressure

Hybrid cars have lately been brought back into policy discussions as automakers have lobbied the EU to weaken CO₂ standards. A proposed ban on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with large automotive industries.

Some senior politicians have proposed plug-in hybrids as a possible “compromise” option to introduce in the legislation.

An independent energy policy expert, who was not involved with the study, called the report a “very useful contribution” after years in which segments of the car sector claimed there was too little data to accurately evaluate actual CO2 output.

“The results demonstrate, beyond any doubt, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or conventional vehicles,” the expert said. “All regulatory adjustments regarding PHEVs should be made with utmost caution and considering this data.”