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Plug-in hybrid electric vehicles produce nearly 5x more planet-heating pollution than official figures show, according to a recent analysis.

Growing Gap Between Official and Actual CO2 Output

Data shows that PHEVs release only 19% lower CO₂ than traditional petrol and diesel cars, according to analysis carried out by a non-profit organization. This differs sharply with laboratory estimates, which assumed a 75% reduction in pollution.

Researchers examined information from onboard fuel consumption monitors of eight hundred thousand cars sold in the EU between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, up from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported figures are decreasing,” stated a senior analyst participating in the study. “That discrepancy is growing and creates a serious issue. As a result, PHEVs pollute nearly as heavily as petrol vehicles.”

Key Reasons Driving the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “utility factor” – the percentage of kilometers driven in electric mode relative to total mileage. They determined that only 27% of travel was done in electric mode, while official assumptions suggested over four-fifths.

Even, when operating in EV mode, emission amounts were well above official estimates. That occurred because EV motors were insufficiently powerful sufficient to operate independently, leading to engines using fossil fuels for nearly one-third of the distance completed in EV mode.

Regulatory and Economic Implications

Based on estimates, the lowballing of PHEV emissions allowed four major automaker companies to escape more than €5bn in fines from 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would spend approximately €500 extra per year in running costs than is assumed under laboratory tests.

“The strong claims that automakers like to make about their PHEV cars are obviously far from the mark,” stated a automotive expert. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are little improved than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating costs.”

Policy Discussion and Industry Lobbying

Plug-in hybrid cars have lately been drawn back into political debates as carmakers have pressed the European Union to relax CO₂ standards. A planned ban on sales of new internal combustion vehicles in 2035 has faced intense pressure from the car sector and opposition from EU countries with significant automotive industries.

Several high-level officials have suggested PHEVs as a possible “compromise” solution to include in the legislation.

An external energy economics expert, who was not involved with the research, called the report a “very useful contribution” after years in which parts of the automotive sector claimed there was insufficient information to accurately evaluate real-world emissions.

“The results show, beyond any doubt, that the difference in official and actual PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or diesel vehicles,” the expert stated. “All policy adjustments concerning PHEVs should be implemented with utmost care and in the light of this evidence.”