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PHEVs produce almost five times more planet-heating pollution than official figures indicate, according to a new report.

Widening Discrepancy In Official and Actual Emissions

Statistics reveals that PHEVs release only one-fifth lower CO₂ than traditional petrol and diesel cars, based on research conducted by a advocacy organization. This differs sharply with lab estimates, which assumed a three-quarters reduction in emissions.

Analysts studied data from in-vehicle energy use monitors of eight hundred thousand cars sold in Europe from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official emissions are decreasing,” said a lead researcher involved in the study. “This gap is widening and creates a significant problem. As a result, PHEVs pollute almost as much as petrol cars.”

Primary Factors Driving the Discrepancy

Researchers attributed the majority of the gap to inflated estimates of the “electric driving share” – the percentage of miles driven in battery mode compared to total distance. The team determined that just a quarter of driving was done in EV mode, whereas official estimates assumed over four-fifths.

Additionally, when running in EV mode, emission amounts were significantly higher than lab estimates. That happened because electric motors were insufficiently powerful sufficient to operate independently, resulting to combustion motors using fossil fuels for nearly one-third of the travel covered in electric mode.

Policy and Financial Implications

According to estimates, the lowballing of PHEV CO2 output enabled four large automaker companies to avoid more than €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ targets.

Furthermore, drivers of PHEVs would spend about €500 extra annually in running costs than is estimated under laboratory conditions.

“The bold statements that automakers often promote about their plug-in hybrid cars are obviously way off the mark,” stated a transport analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of energy use, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have recently been drawn back into political discussions as carmakers have pressed the EU to relax CO₂ standards. A planned prohibition on new combustion engine vehicles in 2035 has faced heavy pressure from the automotive industry and opposition from member states with large automotive manufacturing.

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

One external energy economics specialist, who was unaffiliated with the research, described the analysis a “highly valuable contribution” after a long period in which parts of the car sector claimed there was insufficient data to accurately assess real-world emissions.

“These findings demonstrate, without question, that the difference in lab and real-world PHEV energy use and CO₂ emissions is significantly larger than for petrol or conventional vehicles,” they stated. “Any policy changes concerning PHEVs should be made with extreme caution and in the light of this data.”