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Plug-in hybrid electric vehicles release nearly 5x greater global warming pollution than official figures show, according to a recent report.

Growing Gap In Official and Real-World Emissions

Data reveals that PHEVs emit only one-fifth less CO₂ than conventional petrol and diesel vehicles, based on research carried out by a non-profit organization. That contrasts significantly with lab estimates, which assumed a 75% reduction in pollution.

Analysts studied data from in-vehicle energy use meters of 800,000 vehicles sold in Europe between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported figures are falling,” said a lead analyst involved in the report. “This discrepancy is growing and poses a significant problem. As a result, PHEVs emit almost as heavily as gasoline vehicles.”

Primary Factors Behind the Emissions Gap

Analysts attributed the majority of the difference to overestimates of the “utility factor” – the percentage of kilometers travelled in electric power compared to overall mileage. They found that just 27% of driving was done in EV mode, while lab estimates suggested 84%.

Even, when operating in electric mode, pollution amounts were well above official projections. That occurred because EV motors were insufficiently powerful enough to function independently, resulting to engines burning gasoline for almost one-third of the travel covered in EV mode.

Regulatory and Economic Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled several major automaker companies to avoid over €5bn in penalties between 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ standards.

Furthermore, owners of PHEVs could pay approximately €500 more per year in operating expenses than is estimated under lab tests.

“The bold statements that automakers often promote about their plug-in hybrid vehicles are clearly way off the mark,” stated a automotive analyst. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are only slightly better than regular petrol and diesel cars in terms of fuel use, CO₂ production, and operating expenses.”

Political Debate and Automotive Pressure

Plug-in hybrid vehicles have recently been brought again into policy discussions as automakers have lobbied the European Union to relax CO₂ standards. A proposed prohibition on new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and opposition from member states with significant car industries.

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

One external energy economics expert, who was unaffiliated with the research, called the analysis a “highly valuable addition” after a long period in which parts of the car sector claimed there was too little data to properly evaluate actual CO2 output.

“These findings demonstrate, without question, that the difference between lab and real-world PHEV fuel consumption and CO₂ output is significantly larger than for petrol or diesel vehicles,” the expert stated. “Any policy changes regarding PHEVs should be made with extreme care and in the light of that evidence.”