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Plug-in hybrid cars produce almost 5x greater global warming emissions than official data show, as per a recent report.

Widening Discrepancy In Lab and Real-World CO2 Output

Data reveals that PHEVs release only one-fifth less CO₂ than traditional petrol and diesel vehicles, based on analysis carried out by a advocacy group. This contrasts significantly with laboratory estimates, which suggested a 75% reduction in emissions.

Analysts examined information from in-vehicle energy use meters of eight hundred thousand vehicles registered in Europe from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported figures are decreasing,” said a lead researcher participating in the study. “This gap is widening and poses a serious issue. Consequently, PHEVs emit almost as much as petrol cars.”

Key Reasons Behind the Emissions Gap

Researchers attributed the majority of the difference to overestimates of the “electric driving share” – the percentage of kilometers driven in battery mode compared to total distance. They determined that just 27% of driving was done in electric mode, whereas official estimates suggested over four-fifths.

Even, when running in electric mode, pollution amounts were well above lab estimates. That occurred because electric motors were not strong enough to operate independently, resulting to engines using fossil fuels for almost a third of the distance covered in EV mode.

Regulatory and Financial Implications

Based on calculations, the underestimation of PHEV emissions enabled several large automaker groups to escape more than €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

Additionally, owners of PHEVs could pay approximately €500 extra annually in running expenses than is assumed under laboratory tests.

“The strong statements that manufacturers often promote about their PHEV cars are clearly way off the truth,” commented a transport analyst. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are little better than standard petrol and diesel cars in terms of fuel consumption, CO₂ production, and running expenses.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid vehicles have recently been drawn again into political debates as carmakers have pressed the EU to weaken CO₂ targets. A proposed prohibition on new combustion engine cars in 2035 has faced heavy pressure from the automotive industry and opposition from member states with large automotive industries.

Some high-level politicians have suggested plug-in hybrids as a possible “flexibility” solution to introduce in the legislation.

An external energy economics specialist, who was not involved with the research, described the report a “highly valuable addition” after a long period in which parts of the car sector claimed there was too little data to properly evaluate actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in lab and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or conventional vehicles,” the expert said. “All regulatory changes regarding PHEVs should be implemented with utmost care and in the light of this data.”