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Plug-in hybrid cars emit almost 5x greater global warming emissions than official figures show, according to a recent report.

Widening Gap Between Official and Real-World CO2 Output

Statistics reveals that PHEVs release only 19% less CO₂ than traditional petrol and diesel vehicles, based on analysis carried out by a non-profit group. This contrasts significantly with lab tests, which assumed a three-quarters reduction in pollution.

Researchers examined information from onboard energy use meters of 800,000 vehicles sold in the EU between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official emissions are falling,” stated a senior researcher participating in the study. “That discrepancy is widening and creates a significant issue. Consequently, PHEVs emit almost as heavily as gasoline cars.”

Key Factors Behind the Emissions Gap

Researchers linked most of the gap to overestimates of the “electric driving share” – the percentage of miles travelled in battery power relative to overall distance. The team determined that just 27% of driving was completed in electric mode, while official assumptions suggested 84%.

Additionally, when running in EV mode, pollution amounts were significantly higher than lab estimates. This happened because electric motors were insufficiently powerful sufficient to function alone, resulting to combustion motors burning fossil fuels for nearly one-third of the travel completed in electric mode.

Policy and Economic Implications

According to calculations, the underestimation of PHEV CO2 output allowed several major automaker companies to escape more than €5bn in fines between 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would pay about €500 extra per year in running expenses than is estimated under lab tests.

“The strong claims that automakers often promote about their plug-in hybrid cars are obviously far from the truth,” stated a transport analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and operating expenses.”

Policy Discussion and Industry Lobbying

Hybrid cars have lately been drawn back into political discussions as carmakers have lobbied the EU to weaken CO₂ standards. A planned prohibition on sales of new combustion engine cars in 2035 has faced intense pressure from the automotive sector and opposition from member states with significant car manufacturing.

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

One external energy policy expert, who was not involved with the study, described the analysis a “very useful contribution” after a long period in which segments of the car sector claimed there was insufficient data to accurately assess real-world emissions.

“The results demonstrate, without question, that the gap in lab and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel cars,” the expert stated. “Any regulatory adjustments concerning PHEVs should be implemented with utmost caution and in the light of this data.”