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Plug-in hybrid cars release nearly five times greater planet-heating pollution than official figures indicate, according to a recent report.

Widening Discrepancy Between Official and Actual Emissions

Statistics shows that PHEVs release only one-fifth less CO₂ than conventional petrol and diesel cars, according to analysis carried out by a advocacy group. That differs sharply with laboratory tests, which assumed a three-quarters decrease in emissions.

Analysts examined information from in-vehicle energy use monitors of eight hundred thousand cars registered in the EU from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official emissions are decreasing,” stated a lead analyst involved in the report. “This gap is growing and creates a significant issue. As a result, PHEVs emit almost as heavily as petrol vehicles.”

Primary Reasons Driving the Emissions Gap

Analysts linked most of the gap to inflated estimates of the “utility factor” – the percentage of kilometers driven in battery mode compared to overall mileage. They found that only a quarter of travel was completed in EV mode, whereas official estimates suggested over four-fifths.

Even, when operating in electric mode, pollution amounts were significantly higher than lab projections. This happened because electric motors were insufficiently powerful sufficient to operate independently, leading to engines using fossil fuels for almost a third of the distance covered in EV mode.

Policy and Financial Implications

Based on calculations, the underestimation of PHEV CO2 output allowed several major automaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs would pay approximately €500 more per year in running costs than is estimated under laboratory tests.

“The strong statements that automakers like to make about their PHEV cars are clearly far from the mark,” commented a automotive expert. “Buyers are being duped into believing that by buying a PHEV, they are helping the planet and cutting money. In reality, PHEVs are little better than regular gas and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Debate and Industry Lobbying

Plug-in hybrid cars have recently been drawn again into political debates as automakers have lobbied the European Union to weaken CO₂ targets. A proposed prohibition on new combustion engine cars in 2035 has faced heavy lobbying from the car industry and resistance from member states with significant automotive manufacturing.

Some senior politicians have proposed PHEVs as a potential “flexibility” option to introduce in the regulation.

An external energy policy expert, who was not involved with the research, described the report a “highly valuable contribution” after years in which segments of the car industry claimed there was too little data to properly evaluate actual CO2 output.

“These findings show, 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 stated. “Any policy adjustments concerning PHEVs should be made with extreme care and considering this data.”