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Plug-in hybrid cars release nearly five times more planet-heating emissions than lab-reported figures show, as per a recent report.

Widening Discrepancy Between Lab and Actual CO2 Output

Data reveals that PHEVs emit just one-fifth less CO₂ than conventional petrol and diesel cars, based on research conducted by a advocacy organization. This contrasts sharply with laboratory tests, which suggested a 75% reduction in pollution.

Researchers studied data from onboard energy use monitors of 800,000 vehicles sold in Europe from 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, up from three and a half times in 2021.

“Real-world emissions are rising, while official figures are decreasing,” stated a lead analyst participating in the study. “This discrepancy is widening and poses a serious issue. Consequently, PHEVs pollute nearly as heavily as petrol cars.”

Key Factors Behind the Emissions Gap

Analysts attributed the majority of the difference to overestimates of the “electric driving share” – the percentage of miles driven in electric mode compared to overall mileage. They determined that just 27% of driving was done in electric mode, whereas official estimates suggested 84%.

Additionally, when operating in EV mode, emission levels were significantly higher than lab projections. That occurred because electric motors were not strong sufficient to function independently, leading to engines burning gasoline for almost a third of the travel completed in EV mode.

Policy and Economic Implications

Based on estimates, the underestimation of PHEV emissions allowed four large automaker groups to escape more than €5bn in fines from 2021 and 2023, by falsely simplifying adherence with EU average fleet CO₂ targets.

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

“The bold statements that automakers often promote about their plug-in hybrid cars are obviously way off the mark,” commented a automotive 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 gas and diesel cars in terms of fuel use, CO₂ emissions, and running costs.”

Policy Discussion and Industry Pressure

Plug-in hybrid cars have lately been brought again into policy discussions as carmakers have lobbied the EU to relax CO₂ standards. A planned ban on new internal combustion cars in 2035 has faced heavy lobbying from the car sector and resistance from member states with significant automotive industries.

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

An external energy economics expert, who was not involved with the study, called the analysis a “highly valuable addition” after a long period in which parts of the car industry claimed there was too little data to accurately evaluate real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in official and actual PHEV energy use and CO₂ output is much, much greater than for gasoline or conventional vehicles,” they said. “All policy changes regarding PHEVs should be implemented with utmost caution and considering that evidence.”