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Plug-in hybrid cars produce almost five times more planet-heating emissions than official data show, as per a new report.

Widening Gap In Official and Actual Emissions

Statistics reveals that PHEVs emit only 19% lower CO₂ than traditional petrol and diesel cars, according to research conducted by a advocacy group. This differs significantly with lab estimates, which assumed a three-quarters decrease in pollution.

Researchers studied information from in-vehicle energy use monitors of eight hundred thousand cars sold in the EU between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, up from three and a half times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” stated a senior analyst participating in the report. “That gap is growing and poses a serious issue. As a result, PHEVs emit almost as heavily as gasoline vehicles.”

Key Reasons Behind the Discrepancy

Researchers attributed the majority of the difference to overestimates of the “utility factor” – the ratio of kilometers driven in battery mode relative to total mileage. They found that just a quarter of travel was done in EV mode, while lab estimates suggested over four-fifths.

Even, when running in EV mode, emission amounts were well above official projections. This happened because electric motors were not strong sufficient to operate alone, leading to combustion motors burning fossil fuels for almost a third of the travel completed in EV mode.

Policy and Financial Implications

Based on calculations, the lowballing of PHEV emissions enabled four major carmaker groups to avoid more than €5bn in fines between 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would pay about €500 more per year in running expenses than would be assumed under laboratory tests.

“The bold claims that manufacturers often promote about their PHEV cars are clearly 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 saving costs. In reality, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and running costs.”

Political Discussion and Automotive Lobbying

Plug-in hybrid cars have recently been brought again into policy debates as carmakers have lobbied the EU to relax CO₂ standards. A proposed ban on new combustion engine vehicles in 2035 has faced intense lobbying from the automotive sector and opposition from EU countries with large car industries.

Several senior officials have suggested plug-in hybrids as a potential “compromise” solution to introduce in the legislation.

An independent energy policy expert, who was not involved with the study, called the report a “highly valuable addition” after a long period in which parts of the automotive sector claimed there was insufficient information to accurately assess actual emissions.

“The results show, beyond any doubt, that the difference in official and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional cars,” they said. “All regulatory changes concerning PHEVs should be made with utmost caution and considering that evidence.”