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PHEVs release nearly 5x more global warming pollution than official data indicate, according to a new report.

Growing Discrepancy In Lab and Real-World CO2 Output

Statistics shows that PHEVs release only one-fifth less CO₂ than traditional petrol and diesel cars, based on research carried out by a advocacy organization. That contrasts significantly with lab tests, which assumed a three-quarters reduction in pollution.

Researchers examined data from onboard energy use meters of 800,000 cars sold in the EU between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, increased from three and a half times in 2021.

“Real-world emissions are increasing, while official emissions are falling,” stated a senior analyst involved in the report. “That gap is growing and creates a serious problem. As a result, PHEVs emit nearly as heavily as petrol cars.”

Key Reasons Driving the Discrepancy

Analysts attributed the majority of the gap to inflated estimates of the “utility factor” – the ratio of kilometers travelled in battery power compared to total distance. The team found that just 27% of driving was completed in electric mode, whereas lab assumptions suggested 84%.

Additionally, when running in EV mode, emission levels were well above lab estimates. This happened because electric motors were insufficiently powerful enough to operate alone, resulting to combustion motors using fossil fuels for almost one-third of the travel completed in EV mode.

Policy and Economic Implications

According to calculations, the underestimation of PHEV CO2 output allowed four major automaker groups to avoid more than €5bn in fines between 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs could spend approximately €500 extra annually in operating costs than would be assumed under laboratory tests.

“The strong statements that automakers like to make about their plug-in hybrid vehicles are obviously way off the mark,” stated a transport expert. “Consumers are being misled into thinking that by buying a PHEV, they are helping the planet and saving costs. In reality, PHEVs are only slightly improved than regular petrol and diesel cars in terms of energy consumption, CO₂ emissions, and operating expenses.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have lately been brought back into political debates as automakers have lobbied the European Union to weaken CO₂ standards. A proposed ban on sales of new internal combustion vehicles in 2035 has faced intense pressure from the automotive sector and resistance from EU countries with large car manufacturing.

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

One independent energy economics specialist, who was not involved with the research, described the report a “very useful addition” after a long period in which segments of the car sector argued there was too little data to accurately assess real-world emissions.

“These findings demonstrate, without question, that the difference in lab and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or conventional vehicles,” they stated. “All policy adjustments regarding PHEVs should be implemented with utmost care and in the light of that evidence.”