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PHEVs release almost 5x greater global warming pollution than lab-reported data show, as per a new analysis.

Growing Discrepancy Between Official and Real-World CO2 Output

Statistics reveals that PHEVs release just 19% lower CO₂ than conventional gas and diesel cars, according to analysis carried out by a non-profit organization. This differs sharply with laboratory tests, which suggested a three-quarters reduction in pollution.

Researchers studied information from in-vehicle energy use meters of eight hundred thousand cars registered in the EU from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” said a lead researcher involved in the report. “That gap is growing and poses a serious issue. Consequently, PHEVs pollute nearly as much as petrol vehicles.”

Key Reasons Driving the Emissions Gap

Analysts linked the majority of the difference to overestimates of the “electric driving share” – the percentage of kilometers travelled in electric mode relative to total mileage. The team determined that only 27% of travel was done in electric mode, whereas lab estimates suggested over four-fifths.

Additionally, when operating in electric mode, emission levels were well above official projections. This happened because EV motors were insufficiently powerful sufficient to operate independently, leading to engines using fossil fuels for nearly a third of the distance covered in electric mode.

Regulatory and Economic Implications

Based on calculations, the underestimation of PHEV emissions enabled four large automaker companies to escape over €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could pay approximately €500 extra per year in running costs than would be estimated under laboratory conditions.

“The bold claims that automakers like to make about their PHEV vehicles are clearly way off the truth,” commented a transport expert. “Buyers are being duped into thinking that by buying a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and operating costs.”

Political Discussion and Automotive Lobbying

Hybrid cars have lately been drawn again into policy discussions as automakers have pressed the EU to relax CO₂ standards. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the car industry and opposition from EU countries with large car manufacturing.

Some high-level politicians have proposed PHEVs as a potential “compromise” solution to include in the legislation.

An independent energy economics expert, who was unaffiliated with the research, described the report a “very useful contribution” after years in which parts of the automotive sector argued there was insufficient data to accurately assess actual emissions.

“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 petrol or diesel vehicles,” the expert stated. “Any regulatory adjustments concerning PHEVs should be implemented with extreme care and in the light of this data.”