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Plug-in hybrid electric vehicles emit almost five times greater planet-heating pollution than lab-reported figures indicate, according to a new report.

Widening Gap In Lab and Real-World Emissions

Statistics shows that PHEVs emit only 19% lower CO₂ than conventional petrol and diesel cars, based on research carried out by a advocacy organization. This differs significantly with laboratory tests, which suggested a 75% decrease in pollution.

Researchers studied information from in-vehicle energy use monitors of eight hundred thousand cars sold in Europe 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 rising, while lab-reported figures are falling,” stated a lead analyst participating in the study. “That discrepancy is widening and creates a serious problem. Consequently, PHEVs pollute nearly as much as gasoline cars.”

Primary Reasons Behind the Discrepancy

Researchers linked the majority of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in electric mode relative to total mileage. They found that just a quarter of driving was done in electric mode, whereas lab estimates suggested over four-fifths.

Even, when running in EV mode, emission levels were significantly higher than official projections. That occurred because EV motors were not strong sufficient to operate independently, leading to combustion motors burning gasoline for almost a third of the distance covered in EV mode.

Policy and Financial Consequences

According to calculations, the underestimation of PHEV emissions enabled several large carmaker groups to escape more than €5bn in penalties between 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs could spend approximately €500 extra annually in running expenses than is assumed under lab conditions.

“The strong statements that automakers often promote about their plug-in hybrid vehicles are clearly far from the mark,” commented a automotive analyst. “Consumers are being misled into believing that by buying a PHEV, they are helping the environment and saving costs. Actually, PHEVs are little improved than regular petrol and diesel cars in terms of energy consumption, CO₂ emissions, and running expenses.”

Political Discussion and Automotive Lobbying

Hybrid cars have lately been brought again into political debates as automakers have lobbied the EU to relax CO₂ targets. A proposed ban on new combustion engine vehicles in 2035 has faced heavy lobbying from the car sector and opposition from EU countries with significant automotive manufacturing.

Some senior politicians have proposed PHEVs as a potential “compromise” solution to include in the legislation.

One independent energy economics specialist, who was unaffiliated with the study, described the analysis a “highly valuable contribution” after a long period in which segments of the car industry claimed there was insufficient information to properly assess actual emissions.

“These findings show, without question, that the difference between official and real-world PHEV energy use and CO₂ output is significantly larger than for petrol or diesel cars,” they stated. “All policy changes concerning PHEVs should be made with extreme caution and considering that evidence.”