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Plug-in hybrid cars release nearly 5x greater planet-heating emissions than lab-reported data show, according to a new report.

Growing Gap In Lab and Actual CO2 Output

Data reveals that PHEVs emit only one-fifth lower CO₂ than conventional petrol and diesel vehicles, based on analysis carried out by a non-profit group. This contrasts sharply with lab estimates, which suggested a three-quarters decrease in emissions.

Researchers studied data from onboard fuel consumption meters of 800,000 vehicles sold in Europe between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, up from three and a half times in 2021.

“Real-world CO2 output are rising, while official figures are falling,” said a lead analyst involved in the study. “This gap is widening and poses a significant problem. Consequently, PHEVs emit almost as heavily as gasoline cars.”

Key Reasons Behind the Emissions Gap

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers driven in electric power relative to total distance. The team found that only 27% of travel was completed in EV mode, while lab estimates suggested 84%.

Additionally, when operating in EV mode, pollution levels were significantly higher than official estimates. This happened because EV motors were insufficiently powerful sufficient to operate alone, resulting to combustion motors using fossil fuels for nearly one-third of the travel covered in electric mode.

Regulatory and Financial Implications

According to estimates, the lowballing of PHEV emissions enabled several major automaker companies to escape over €5bn in fines from 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs could pay approximately €500 extra annually in running costs than is assumed under lab conditions.

“The bold claims that manufacturers often promote about their plug-in hybrid vehicles are obviously far from the truth,” stated a automotive expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are little better than regular gas and diesel cars in terms of fuel consumption, CO₂ production, and operating costs.”

Political Debate and Industry Pressure

Hybrid vehicles have lately been drawn again into political debates as automakers have lobbied the European Union to relax CO₂ standards. A planned ban on new internal combustion vehicles in 2035 has faced heavy pressure from the car sector and opposition from EU countries with large car industries.

Some high-level politicians have proposed plug-in hybrids as a possible “compromise” solution to introduce in the regulation.

One external energy policy specialist, who was unaffiliated with the research, called the report a “highly valuable addition” after years in which segments of the automotive sector argued there was insufficient data to properly assess actual emissions.

“The results demonstrate, beyond any doubt, that the gap in official and real-world PHEV fuel consumption and CO₂ output is much, much larger than for gasoline or conventional cars,” they stated. “All policy adjustments regarding PHEVs should be made with extreme care and in the light of this data.”