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Plug-in hybrid cars produce almost five times more global warming emissions than lab-reported figures show, as per a new analysis.

Growing Gap In Official and Real-World CO2 Output

Statistics shows that PHEVs release only 19% lower CO₂ than conventional gas and diesel vehicles, according to analysis carried out by a non-profit group. This contrasts sharply with laboratory estimates, which assumed a 75% reduction in emissions.

Researchers examined information from onboard fuel consumption monitors of 800,000 vehicles sold in Europe from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, up from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are decreasing,” stated a senior analyst involved in the report. “This gap is widening and poses a significant problem. Consequently, PHEVs pollute nearly as much as gasoline cars.”

Key Reasons Driving the Discrepancy

Analysts attributed most of the gap to overestimates of the “electric driving share” – the percentage of kilometers travelled in battery power compared to overall mileage. The team found that only 27% of travel was completed in electric mode, whereas lab estimates assumed over four-fifths.

Even, when operating in electric mode, pollution levels were well above official estimates. That occurred because EV motors were insufficiently powerful sufficient to function independently, resulting to engines burning gasoline for nearly one-third of the distance completed in EV mode.

Policy and Economic Implications

Based on calculations, the underestimation of PHEV emissions enabled four major automaker groups to escape over €5bn in fines from 2021 and 2023, by falsely simplifying adherence with EU fleet-average CO₂ targets.

Furthermore, drivers of PHEVs would spend approximately €500 extra annually in operating costs than would be estimated under lab conditions.

“The bold claims that automakers often promote about their PHEV cars are obviously way off the mark,” commented a automotive analyst. “Consumers are being misled into thinking that by buying a PHEV, they are helping the planet and cutting money. In reality, PHEVs are little better than regular gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating expenses.”

Policy Debate and Industry Lobbying

Plug-in hybrid cars have lately been brought again into policy discussions as automakers have pressed the EU to weaken CO₂ standards. A proposed ban on sales of new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and opposition from EU countries with large automotive industries.

Several high-level officials have suggested PHEVs as a potential “compromise” solution to introduce in the regulation.

An independent energy policy expert, who was not involved with the research, described the analysis a “highly valuable addition” after years in which segments of the car sector claimed there was insufficient information to properly assess actual emissions.

“The results demonstrate, beyond any doubt, that the gap in official and actual PHEV energy use and CO₂ output is much, much larger than for petrol or conventional cars,” they said. “All policy changes regarding PHEVs should be implemented with utmost care and considering that evidence.”