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Plug-in hybrid electric vehicles produce almost five times more planet-heating pollution than official data indicate, as per a recent report.

Growing Gap In Official and Actual Emissions

Data reveals that PHEVs release only 19% less CO₂ than conventional petrol and diesel vehicles, according to analysis conducted by a advocacy group. That contrasts sharply with lab estimates, which assumed a three-quarters decrease in emissions.

Researchers studied information from in-vehicle energy use monitors of 800,000 cars registered in the EU from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, up from three and a half times in 2021.

“Real-world CO2 output are rising, while official figures are decreasing,” said a senior analyst participating in the report. “That discrepancy is widening and poses a serious problem. Consequently, PHEVs pollute nearly as much as petrol cars.”

Key Reasons Driving the Emissions Gap

Researchers linked most of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in battery mode relative to overall distance. They determined that only a quarter of travel was done in EV mode, whereas lab estimates suggested 84%.

Additionally, when running in electric mode, emission amounts were significantly higher than lab estimates. This happened because EV motors were not strong sufficient to function alone, leading to engines burning fossil fuels for nearly one-third of the distance completed in electric mode.

Policy and Financial Consequences

According to calculations, the lowballing of PHEV emissions allowed four large carmaker groups to escape over €5bn in fines from 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs would spend about €500 more per year in operating expenses than would be assumed under laboratory conditions.

“The strong statements that automakers often promote about their plug-in hybrid cars are clearly far from the mark,” commented a automotive analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the planet and saving costs. Actually, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy consumption, CO₂ production, and running expenses.”

Political Debate and Industry Lobbying

Hybrid cars have recently been brought back into policy discussions as carmakers have pressed the European Union to relax CO₂ standards. A planned prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with large automotive industries.

Some senior politicians have proposed plug-in hybrids as a possible “flexibility” solution to introduce in the regulation.

An independent energy economics specialist, who was unaffiliated with the research, called the report a “very useful addition” after years in which segments of the car sector claimed there was too little information to accurately assess actual CO2 output.

“The results show, without question, that the difference between official and actual PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or diesel vehicles,” the expert said. “Any policy adjustments regarding PHEVs should be implemented with extreme caution and considering that data.”