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Plug-in hybrid cars produce almost five times greater planet-heating pollution than official data indicate, according to a recent report.

Widening Discrepancy In Lab and Real-World Emissions

Data reveals that PHEVs emit only one-fifth lower CO₂ than conventional gas and diesel vehicles, according to research carried out by a non-profit organization. This contrasts significantly with lab tests, which assumed a 75% reduction in pollution.

Researchers studied data from onboard fuel consumption meters of 800,000 cars sold in the EU from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, up from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are decreasing,” stated a lead analyst involved in the study. “That discrepancy is growing and poses a significant issue. As a result, PHEVs pollute nearly as heavily as petrol cars.”

Key Factors Driving the Emissions Gap

Researchers linked most of the difference to inflated estimates of the “utility factor” – the percentage of kilometers travelled in battery mode compared to overall mileage. They found that only 27% of travel was completed in electric mode, whereas official assumptions suggested 84%.

Even, when operating in EV mode, pollution amounts were significantly higher than lab estimates. That happened because EV motors were not strong sufficient to operate independently, resulting to combustion motors using gasoline for almost a third of the travel completed in EV mode.

Policy and Financial Consequences

According to estimates, the lowballing of PHEV emissions allowed several large automaker groups to avoid over €5bn in fines between 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs could spend approximately €500 more per year in operating expenses than is estimated under laboratory conditions.

“The strong statements that manufacturers like to make about their plug-in hybrid vehicles are obviously far from the truth,” stated a automotive analyst. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are only slightly better than regular gas and diesel cars in terms of energy consumption, CO₂ production, and operating costs.”

Political Debate and Industry Lobbying

Plug-in hybrid cars have lately been brought back into policy discussions as carmakers have lobbied the EU to relax CO₂ targets. A planned prohibition on sales of new combustion engine cars in 2035 has faced heavy lobbying from the car sector and resistance from EU countries with significant automotive industries.

Several high-level officials have proposed PHEVs as a potential “flexibility” solution to include in the legislation.

An independent energy economics specialist, who was unaffiliated with the study, called the analysis a “very useful contribution” after a long period in which segments of the car industry claimed there was too little data to properly evaluate real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the gap in lab and real-world PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or diesel vehicles,” they said. “Any regulatory adjustments concerning PHEVs should be made with utmost care and considering that data.”