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Plug-in hybrid electric vehicles produce almost five times greater global warming emissions than official data indicate, as per a new report.

Widening Gap In Lab and Real-World CO2 Output

Data shows that PHEVs emit only 19% lower CO₂ than conventional gas and diesel cars, based on analysis carried out by a advocacy organization. This contrasts sharply with laboratory estimates, which assumed a 75% reduction in pollution.

Researchers studied information from onboard energy use monitors of eight hundred thousand vehicles sold in the EU between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, up from three and a half times in 2021.

“Real-world emissions are increasing, while official emissions are decreasing,” stated a lead analyst involved in the report. “That gap is widening and creates a serious issue. As a result, PHEVs pollute nearly as much as petrol cars.”

Key Reasons Driving the Emissions Gap

Analysts linked most of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric power compared to total distance. The team found that just 27% of travel was done in EV mode, while official estimates suggested 84%.

Additionally, when operating in EV mode, emission amounts were well above lab estimates. This occurred because electric motors were not strong enough to operate independently, resulting to engines using fossil fuels for almost one-third of the distance completed in EV mode.

Regulatory and Economic Implications

According to estimates, the lowballing of PHEV emissions allowed several large automaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs could spend approximately €500 extra per year in running expenses than is estimated under lab tests.

“The bold claims that manufacturers often promote about their PHEV vehicles are clearly far from the truth,” stated a automotive analyst. “Consumers are being misled into believing that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and running expenses.”

Policy Debate and Industry Pressure

Hybrid vehicles have recently been drawn again into policy discussions as carmakers have pressed the EU to relax CO₂ targets. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with large car manufacturing.

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

An independent energy policy specialist, who was not involved with the study, described the report a “highly valuable addition” after years in which parts of the car sector argued there was too little information to properly assess actual emissions.

“The results show, without question, that the gap in official and actual PHEV fuel consumption and CO₂ output is much, much greater than for petrol or conventional cars,” the expert said. “Any regulatory adjustments regarding PHEVs should be made with utmost caution and considering this data.”