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Plug-in hybrid electric vehicles emit almost five times greater planet-heating emissions than lab-reported figures show, as per a new report.

Widening Discrepancy Between Official and Real-World Emissions

Statistics shows that PHEVs release just one-fifth less CO₂ than traditional gas and diesel vehicles, according to research carried out by a advocacy organization. That differs significantly with lab tests, which assumed a 75% decrease in pollution.

Researchers examined information from onboard fuel consumption monitors of 800,000 cars sold in the EU from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official estimates, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are decreasing,” stated a lead analyst involved in the report. “That discrepancy is widening and creates a serious problem. As a result, PHEVs pollute nearly as much as petrol vehicles.”

Primary Factors Behind the Emissions Gap

Researchers attributed the majority of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers driven in battery power compared to overall distance. The team determined that just a quarter of travel was done in EV mode, whereas lab assumptions suggested 84%.

Even, when operating in EV mode, pollution levels were well above official estimates. That happened because EV motors were not strong sufficient to operate alone, leading to combustion motors using gasoline for nearly a third of the travel covered in electric mode.

Regulatory and Economic Consequences

According to estimates, the lowballing of PHEV CO2 output enabled four large carmaker companies to avoid more than €5bn in fines between 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could pay about €500 extra annually in operating expenses than would be estimated under laboratory conditions.

“The bold claims that automakers often promote about their PHEV cars are clearly far from the mark,” stated a transport expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are only slightly better than regular gas and diesel vehicles in terms of fuel use, CO₂ production, and operating expenses.”

Political Debate and Industry Pressure

Hybrid cars have lately been brought again into political discussions as automakers have lobbied the EU to relax CO₂ targets. A proposed prohibition on new internal combustion cars in 2035 has faced intense pressure from the car industry and opposition from member states with significant automotive manufacturing.

Some senior officials have suggested PHEVs as a potential “compromise” solution to introduce in the regulation.

One independent energy policy specialist, who was unaffiliated with the study, described the analysis a “highly valuable contribution” after a long period in which segments of the automotive industry argued there was too little data to properly evaluate real-world CO2 output.

“The results show, without question, that the difference between official and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or diesel vehicles,” the expert stated. “Any regulatory changes concerning PHEVs should be implemented with extreme caution and considering this evidence.”