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Plug-in hybrid cars emit nearly five times more planet-heating emissions than official data show, as per a new analysis.

Growing Gap In Lab and Actual CO2 Output

Data reveals that PHEVs release only 19% less CO₂ than traditional gas and diesel cars, based on research carried out by a advocacy group. This differs significantly with lab tests, which assumed a 75% reduction in emissions.

Analysts examined data from onboard energy use monitors of 800,000 cars sold in Europe from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, up from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are decreasing,” said a lead researcher involved in the report. “That discrepancy is widening and poses a serious issue. Consequently, PHEVs emit nearly as much as petrol vehicles.”

Key Factors Driving the Emissions Gap

Researchers attributed most of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in battery power compared to total mileage. They determined that only a quarter of travel was done in EV mode, whereas official estimates assumed 84%.

Even, when running in electric mode, pollution levels were significantly higher than lab estimates. This occurred because EV motors were not strong enough to function independently, leading to combustion motors burning fossil fuels for almost one-third of the travel completed in EV mode.

Regulatory and Financial Implications

Based on calculations, the lowballing of PHEV CO2 output allowed several large automaker companies to escape over €5bn in fines between 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ targets.

Furthermore, owners of PHEVs could spend about €500 extra annually in operating costs than is estimated under laboratory conditions.

“The bold statements that manufacturers like to make about their PHEV vehicles are clearly far from the truth,” stated a transport expert. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly improved than standard gas and diesel cars in terms of energy use, CO₂ production, and operating costs.”

Policy Discussion and Industry Pressure

Hybrid cars have recently been brought back into political debates as automakers have lobbied the European Union to relax CO₂ targets. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the car sector and opposition from member states with large automotive industries.

Several high-level politicians have proposed PHEVs as a potential “flexibility” option to introduce in the legislation.

One independent energy policy expert, who was not involved with the study, called the report a “very useful addition” after a long period in which segments of the car industry claimed there was too little information to accurately evaluate real-world CO2 output.

“These findings demonstrate, without question, that the difference between lab and actual PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or conventional vehicles,” they stated. “Any policy changes regarding PHEVs should be made with utmost caution and in the light of this evidence.”