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Plug-in hybrid electric vehicles release nearly five times more global warming pollution than lab-reported figures show, as per a recent report.

Widening Discrepancy Between Official and Real-World Emissions

Data shows that PHEVs release only one-fifth less CO₂ than conventional petrol and diesel cars, based on analysis conducted by a advocacy organization. This differs significantly with lab tests, which assumed a 75% decrease in pollution.

Analysts examined information from onboard energy use meters of eight hundred thousand cars sold in Europe between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while official figures are falling,” said a senior analyst involved in the study. “This discrepancy is growing and poses a significant problem. As a result, PHEVs pollute nearly as much as petrol cars.”

Key Factors Driving the Emissions Gap

Researchers linked most of the gap to inflated estimates of the “utility factor” – the percentage of miles travelled in battery mode relative to total distance. They determined that only a quarter of travel was done in EV mode, while lab assumptions assumed 84%.

Even, when running in electric mode, emission levels were well above official estimates. That occurred because EV motors were not strong sufficient to function alone, leading to combustion motors using fossil fuels for almost one-third of the distance covered in electric mode.

Regulatory and Financial Consequences

According to calculations, the underestimation of PHEV emissions enabled several large carmaker groups to avoid over €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ standards.

Furthermore, owners of PHEVs would spend approximately €500 extra annually in operating expenses than would be estimated under laboratory tests.

“The bold claims that automakers often promote about their PHEV cars are clearly far from the truth,” stated a transport expert. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are little improved than regular petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and operating costs.”

Political Debate and Industry Pressure

Plug-in hybrid vehicles have lately been drawn back into policy discussions as carmakers have pressed the European Union to weaken CO₂ standards. A planned prohibition on sales of new combustion engine cars in 2035 has faced heavy lobbying from the automotive sector and opposition from EU countries with large car industries.

Some senior politicians have suggested plug-in hybrids as a possible “compromise” solution to introduce in the legislation.

One independent energy policy specialist, who was unaffiliated with the study, described the report a “highly valuable addition” after years in which parts of the automotive sector claimed there was insufficient information to properly assess real-world CO2 output.

“These findings demonstrate, without question, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or diesel cars,” they said. “Any regulatory adjustments regarding PHEVs should be made with extreme caution and in the light of that evidence.”