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Plug-in hybrid electric vehicles release nearly five times greater planet-heating emissions than official figures show, as per a new report.

Widening Gap Between Lab and Actual Emissions

Data reveals that PHEVs release just one-fifth less CO₂ than traditional petrol and diesel vehicles, based on research conducted by a non-profit group. This differs significantly with lab tests, which suggested a 75% decrease in pollution.

Analysts studied data from onboard energy use monitors of 800,000 cars registered in the EU between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, increased from three and a half times in 2021.

“Actual emissions are rising, while official figures are decreasing,” stated a lead analyst participating in the report. “That discrepancy is widening and creates a significant issue. Consequently, PHEVs pollute almost as heavily as gasoline cars.”

Primary Reasons Behind the Discrepancy

Researchers attributed the majority of the gap to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric mode compared to overall mileage. The team determined that only a quarter of driving was completed in electric mode, whereas official assumptions suggested 84%.

Even, when operating in EV mode, pollution levels were significantly higher than official estimates. That happened because electric motors were not strong sufficient to operate alone, leading to engines using fossil fuels for nearly a third of the travel covered in electric mode.

Regulatory and Financial Consequences

Based on calculations, the lowballing of PHEV emissions allowed four large automaker companies to escape more than €5bn in penalties from 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ targets.

Furthermore, drivers of PHEVs could spend about €500 extra annually in running costs than would be assumed under laboratory tests.

“The strong statements that manufacturers like to make about their plug-in hybrid vehicles are obviously far from the mark,” commented a automotive expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are only slightly improved than regular petrol and diesel cars in terms of energy use, CO₂ production, and operating costs.”

Political Discussion and Industry Pressure

Plug-in hybrid cars have recently been brought back into political debates as automakers have pressed the European Union to relax CO₂ standards. A proposed ban on new combustion engine cars in 2035 has faced intense lobbying from the car sector and resistance from member states with large car manufacturing.

Some high-level officials have proposed plug-in hybrids as a potential “compromise” option to include in the legislation.

An external energy economics specialist, who was not involved with the research, called the report a “very useful addition” after years in which segments of the automotive industry claimed there was insufficient data to accurately evaluate actual emissions.

“These findings demonstrate, without question, that the difference in official and real-world PHEV energy use and CO₂ output is significantly greater than for petrol or diesel cars,” they said. “All policy adjustments concerning PHEVs should be implemented with extreme care and in the light of that data.”