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PHEVs produce nearly 5x more planet-heating emissions than official data indicate, according to a new report.

Growing Discrepancy In Official and Actual Emissions

Statistics shows that PHEVs release only 19% less CO₂ than traditional petrol and diesel vehicles, based on analysis conducted by a non-profit organization. That contrasts sharply with lab tests, which suggested a three-quarters decrease in pollution.

Researchers examined data from in-vehicle fuel consumption meters of 800,000 cars registered in Europe from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, increased from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported emissions are decreasing,” said a senior researcher involved in the report. “That discrepancy is widening and creates a serious issue. Consequently, PHEVs emit almost as heavily as gasoline cars.”

Primary Reasons Behind the Discrepancy

Analysts attributed most of the difference to overestimates of the “electric driving share” – the percentage of miles travelled in electric power relative to overall distance. The team found that only 27% of driving was done in electric mode, while official assumptions suggested over four-fifths.

Even, when running in EV mode, pollution levels were well above official projections. This occurred because electric motors were not strong sufficient to function independently, resulting to engines using fossil fuels for nearly one-third of the distance covered in EV mode.

Policy and Economic Implications

According to estimates, the lowballing of PHEV emissions allowed several large carmaker groups to escape over €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs would spend about €500 more annually in running expenses than is estimated under laboratory tests.

“The bold claims that manufacturers often promote about their PHEV cars are clearly far from the truth,” stated a transport expert. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are only slightly improved than standard gas and diesel cars in terms of energy use, CO₂ emissions, and running costs.”

Policy Discussion and Automotive Lobbying

Hybrid vehicles have recently been brought back into political debates as automakers have pressed the European Union to weaken CO₂ standards. A proposed ban on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the automotive industry and resistance from EU countries with significant car manufacturing.

Several high-level officials have proposed PHEVs as a potential “compromise” option to introduce in the legislation.

One independent energy economics specialist, who was not involved with the study, called the report a “very useful contribution” after a long period in which parts of the automotive sector argued there was insufficient information to properly evaluate actual emissions.

“These findings show, beyond any doubt, that the gap in lab and real-world PHEV fuel consumption and CO₂ output is much, much larger than for gasoline or conventional cars,” they said. “Any policy adjustments concerning PHEVs should be made with utmost care and in the light of that evidence.”