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PHEVs emit nearly five times greater planet-heating pollution than lab-reported data indicate, as per a new analysis.

Widening Discrepancy Between Lab and Real-World CO2 Output

Data shows that PHEVs emit just one-fifth less CO₂ than conventional petrol and diesel cars, based on research carried out by a advocacy group. That differs sharply with lab estimates, which suggested a 75% reduction in pollution.

Analysts studied data from in-vehicle fuel consumption meters of eight hundred thousand vehicles sold in the EU between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, increased from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported figures are falling,” stated a lead analyst involved in the report. “This gap is widening and poses a significant problem. As a result, PHEVs emit almost as much as gasoline vehicles.”

Key Factors Behind the Emissions Gap

Analysts linked the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers travelled in electric mode compared to overall mileage. The team determined that just 27% of travel was done in electric mode, whereas official estimates suggested 84%.

Additionally, when running in EV mode, pollution levels were well above lab estimates. That happened because electric motors were insufficiently powerful enough to operate independently, resulting to combustion motors using fossil fuels for nearly one-third of the distance covered in EV mode.

Policy and Economic Implications

According to estimates, the underestimation of PHEV CO2 output enabled four major automaker groups to escape over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could pay approximately €500 more per year in operating expenses than would be estimated under lab conditions.

“The bold claims that manufacturers often promote about their PHEV vehicles are clearly way off the mark,” stated a transport expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are only slightly better than standard gas and diesel cars in terms of energy consumption, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have lately been drawn again into political discussions as automakers have pressed the EU to relax CO₂ standards. A planned ban on sales of new internal combustion vehicles in 2035 has faced intense pressure from the automotive industry and resistance from EU countries with large automotive industries.

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

One independent energy economics specialist, who was not involved with the study, described the report a “very useful contribution” after a long period in which segments of the automotive sector argued there was insufficient information to accurately evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the difference between lab and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or diesel cars,” they stated. “All policy adjustments regarding PHEVs should be made with extreme caution and considering this data.”