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Plug-in hybrid electric vehicles emit almost five times more planet-heating emissions than lab-reported figures show, as per a new report.

Growing Gap In Lab and Real-World CO2 Output

Data reveals that PHEVs emit only 19% lower CO₂ than conventional gas and diesel cars, according to analysis carried out by a advocacy organization. This contrasts sharply with lab tests, which assumed a 75% reduction in emissions.

Analysts examined information from onboard fuel consumption meters of eight hundred thousand cars sold in the EU from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, up from three and a half times in 2021.

“Actual emissions are rising, while lab-reported figures are falling,” said a senior analyst involved in the report. “That discrepancy is growing and creates a significant problem. Consequently, PHEVs emit nearly as much as petrol cars.”

Key Factors Driving the Emissions Gap

Researchers attributed the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers driven in electric mode compared to total mileage. The team found that only 27% of driving was done in EV mode, while lab estimates suggested over four-fifths.

Additionally, when operating in EV mode, pollution levels were significantly higher than lab projections. This happened because electric motors were insufficiently powerful enough to function alone, resulting to combustion motors burning gasoline for almost a third of the distance covered in EV mode.

Regulatory and Financial Implications

Based on calculations, the lowballing of PHEV emissions enabled four major automaker groups to escape more than €5bn in penalties between 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would pay approximately €500 more per year in operating expenses than is assumed under laboratory tests.

“The strong claims that manufacturers often promote about their plug-in hybrid cars are obviously far from the mark,” stated a transport analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are only slightly better than standard petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and running expenses.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been brought back into political discussions as automakers have lobbied the European Union to relax CO₂ targets. A planned ban on sales of new combustion engine cars in 2035 has faced heavy pressure from the car industry and opposition from EU countries with significant car industries.

Some senior politicians have proposed plug-in hybrids as a potential “flexibility” option to include in the legislation.

An external energy economics specialist, who was unaffiliated with the research, called the report a “very useful addition” after years in which segments of the car industry claimed there was insufficient data to properly evaluate real-world CO2 output.

“These findings show, beyond any doubt, that the gap in official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or diesel vehicles,” the expert stated. “Any regulatory changes regarding PHEVs should be implemented with utmost caution and in the light of this data.”