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PHEVs emit nearly 5x more global warming pollution than lab-reported data show, according to a new analysis.

Growing Discrepancy In Official and Actual CO2 Output

Data reveals that PHEVs emit only 19% less CO₂ than traditional gas and diesel cars, according to analysis conducted by a advocacy group. This contrasts sharply with laboratory estimates, which suggested a 75% reduction in emissions.

Researchers examined data from in-vehicle energy use monitors of 800,000 vehicles sold in Europe between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, increased from three and a half times in 2021.

“Actual emissions are increasing, while official emissions are decreasing,” said a senior analyst involved in the report. “That gap is growing and poses a serious problem. Consequently, PHEVs pollute nearly as much as gasoline vehicles.”

Key Reasons Behind the Emissions Gap

Analysts attributed most of the gap to overestimates of the “electric driving share” – the percentage of kilometers driven in battery power compared to total mileage. They found that just 27% of travel was done in electric mode, while lab estimates suggested 84%.

Even, when running in electric mode, pollution amounts were well above official estimates. That happened because EV motors were insufficiently powerful sufficient to operate independently, resulting to combustion motors using gasoline for almost a third of the distance covered in EV mode.

Policy and Economic Implications

According to estimates, the underestimation of PHEV emissions enabled several large automaker groups to escape over €5bn in fines between 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs would spend approximately €500 more annually in operating costs than is estimated under laboratory conditions.

“The bold claims that manufacturers often promote about their PHEV cars are obviously far from the mark,” commented a transport expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are only slightly improved than standard gas and diesel cars in terms of fuel consumption, CO₂ emissions, and operating expenses.”

Political Discussion and Automotive Pressure

Plug-in hybrid vehicles have recently been drawn back into policy discussions as automakers have lobbied the European Union to relax CO₂ targets. A proposed ban on sales of new combustion engine cars in 2035 has faced heavy pressure from the automotive industry and opposition from EU countries with significant car manufacturing.

Several high-level officials have suggested PHEVs as a potential “flexibility” solution to include in the regulation.

One external energy economics specialist, who was not involved with the research, called the report a “very useful addition” after a long period in which parts of the automotive sector argued there was insufficient data to accurately assess actual emissions.

“These findings demonstrate, without question, that the gap between lab and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or diesel cars,” they stated. “All policy adjustments regarding PHEVs should be implemented with utmost caution and in the light of this evidence.”