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Plug-in hybrid cars release almost 5x more planet-heating emissions than lab-reported data show, as per a recent report.

Widening Gap In Official and Real-World CO2 Output

Statistics reveals that PHEVs release only 19% lower CO₂ than conventional petrol and diesel vehicles, according to analysis carried out by a non-profit organization. That differs sharply with lab tests, which suggested a three-quarters decrease in emissions.

Researchers examined data from in-vehicle energy use monitors of eight hundred thousand vehicles registered in Europe between 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official figures, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are falling,” stated a senior researcher involved in the report. “This discrepancy is widening and creates a significant issue. Consequently, PHEVs emit almost as heavily as petrol vehicles.”

Primary Reasons Driving the Emissions Gap

Analysts linked most of the gap to overestimates of the “utility factor” – the percentage of miles driven in electric power relative to overall mileage. The team found that only a quarter of travel was completed in electric mode, while official estimates assumed 84%.

Additionally, when running in EV mode, pollution amounts were well above lab projections. This happened because electric motors were insufficiently powerful sufficient to function independently, resulting to engines using fossil fuels for nearly one-third of the travel covered in electric mode.

Policy and Economic Consequences

Based on estimates, the underestimation of PHEV emissions allowed four major carmaker groups to avoid more than €5bn in fines between 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could pay approximately €500 extra annually in running costs than is assumed under laboratory conditions.

“The bold statements that automakers like to make about their PHEV vehicles are clearly way off the mark,” commented a automotive analyst. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of energy use, CO₂ production, and running expenses.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been brought again into policy debates as carmakers have pressed the EU to relax CO₂ targets. A proposed ban on sales of new internal combustion cars in 2035 has faced intense pressure from the automotive industry and opposition from member states with large car industries.

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

One external energy policy specialist, who was unaffiliated with the study, called the analysis a “highly valuable addition” after years in which segments of the car sector claimed there was insufficient data to accurately assess actual CO2 output.

“These findings show, without question, that the difference in lab and actual PHEV energy use and CO₂ emissions is much, much larger than for gasoline or conventional vehicles,” the expert stated. “Any regulatory changes concerning PHEVs should be made with extreme care and in the light of that evidence.”