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PHEVs emit nearly five times more planet-heating emissions than official data indicate, as per a new analysis.

Growing Gap In Lab and Real-World Emissions

Statistics shows that PHEVs emit just 19% lower CO₂ than conventional gas and diesel vehicles, according to analysis conducted by a advocacy group. That contrasts sharply with laboratory estimates, which assumed a three-quarters reduction in emissions.

Analysts examined information from onboard energy use meters of 800,000 cars sold in the EU between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, increased from 3.5 times in 2021.

“Actual emissions are increasing, while official emissions are falling,” stated a lead analyst involved in the report. “This gap is widening and poses a significant issue. As a result, PHEVs pollute nearly as heavily as petrol cars.”

Primary Factors Behind the Discrepancy

Researchers attributed most of the gap to overestimates of the “electric driving share” – the ratio of miles driven in battery mode compared to overall distance. They found that just 27% of travel was completed in electric mode, while lab estimates suggested over four-fifths.

Additionally, when running in electric mode, emission amounts were significantly higher than lab estimates. That happened because EV motors were not strong sufficient to function alone, resulting to engines burning fossil fuels for nearly a third of the travel covered in EV mode.

Policy and Economic Implications

According to estimates, the underestimation of PHEV emissions enabled four major carmaker groups to escape over €5bn in fines between 2021 and 2023, by artificially easing adherence with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs would pay approximately €500 extra per year in operating expenses than would be assumed under lab tests.

“The strong statements that manufacturers often promote about their PHEV vehicles are clearly way off the truth,” stated a automotive expert. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving costs. In reality, PHEVs are little better than standard gas and diesel cars in terms of fuel consumption, CO₂ emissions, and running costs.”

Policy Debate and Automotive Lobbying

Plug-in hybrid cars have lately been drawn back into political discussions as automakers have lobbied the European Union to relax CO₂ targets. A proposed prohibition on new combustion engine vehicles in 2035 has faced heavy pressure from the automotive sector and resistance from EU countries with significant car manufacturing.

Some senior politicians have suggested plug-in hybrids as a potential “flexibility” solution to introduce in the regulation.

One external energy policy specialist, who was not involved with the study, called the report a “highly valuable contribution” after years in which parts of the car sector argued there was too little data to accurately evaluate real-world emissions.

“The results demonstrate, beyond any doubt, that the difference between official and real-world PHEV fuel consumption and CO₂ output is much, much larger than for petrol or diesel vehicles,” they said. “Any regulatory changes concerning PHEVs should be implemented with utmost care and in the light of that evidence.”