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PHEVs release nearly five times more planet-heating emissions than official figures indicate, according to a new report.

Growing Discrepancy Between Lab and Actual CO2 Output

Data reveals that PHEVs emit just one-fifth lower CO₂ than conventional petrol and diesel vehicles, based on research carried out by a non-profit organization. That differs significantly with lab estimates, which suggested a 75% reduction in emissions.

Researchers studied data from in-vehicle energy use meters of 800,000 vehicles registered in the EU from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, up from three and a half times in 2021.

“Real-world emissions are rising, while official emissions are falling,” stated a lead analyst participating in the study. “That gap is widening and creates a significant issue. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Key Factors Driving the Emissions Gap

Researchers linked the majority of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers driven in electric power compared to overall mileage. They determined that only a quarter of travel was completed in electric mode, while lab assumptions suggested 84%.

Additionally, when operating in electric mode, emission amounts were well above official estimates. That happened because EV motors were not strong enough to function alone, leading to combustion motors burning gasoline for almost a third of the travel covered in EV mode.

Regulatory and Financial Consequences

Based on calculations, the lowballing of PHEV emissions allowed several major carmaker groups to avoid more than €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ targets.

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

“The strong statements that automakers often promote about their plug-in hybrid vehicles are obviously far from the truth,” commented a automotive expert. “Consumers are being duped into believing that by buying a PHEV, they are helping the environment and saving costs. In reality, PHEVs are only slightly better than standard petrol and diesel cars in terms of fuel use, CO₂ production, and operating expenses.”

Policy Discussion and Automotive Lobbying

Hybrid cars have lately been drawn back into political debates as carmakers have lobbied the EU to weaken CO₂ targets. A proposed prohibition on new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and resistance from EU countries with significant automotive industries.

Some high-level politicians have suggested PHEVs as a potential “flexibility” option to include in the legislation.

One external energy economics specialist, who was not involved with the study, described the analysis a “highly valuable addition” after a long period in which segments of the car industry argued there was too little data to accurately assess actual emissions.

“These findings show, without question, that the gap in lab and real-world PHEV energy use and CO₂ emissions is significantly greater than for gasoline or diesel vehicles,” they stated. “All policy adjustments regarding PHEVs should be made with extreme caution and considering this evidence.”