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Plug-in hybrid electric vehicles release nearly 5x more planet-heating emissions than lab-reported figures show, as per a recent report.

Growing Gap Between Lab and Real-World Emissions

Statistics reveals that PHEVs release just 19% less CO₂ than traditional gas and diesel vehicles, according to analysis conducted by a advocacy organization. That differs significantly with laboratory tests, which suggested a three-quarters reduction in pollution.

Researchers examined data from onboard energy use meters of eight hundred thousand cars registered in Europe between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, up from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are decreasing,” said a senior researcher involved in the report. “This discrepancy is widening and poses a significant problem. Consequently, PHEVs emit almost as much as gasoline cars.”

Primary Factors Driving the Discrepancy

Analysts attributed most of the gap to overestimates of the “utility factor” – the percentage of miles travelled in electric mode compared to total mileage. The team found that just 27% of travel was completed in EV mode, whereas lab assumptions suggested over four-fifths.

Additionally, when running in EV mode, pollution amounts were well above lab estimates. This occurred because EV motors were not strong sufficient to function alone, leading to engines burning gasoline for almost a third of the distance completed in electric mode.

Policy and Economic Consequences

Based on calculations, the underestimation of PHEV emissions enabled several major automaker groups to escape over €5bn in fines between 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ standards.

Additionally, owners of PHEVs could pay approximately €500 more annually in operating costs than is estimated under laboratory tests.

“The strong statements that manufacturers often promote about their plug-in hybrid vehicles are clearly far from the mark,” stated a automotive expert. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Political Discussion and Industry Pressure

Plug-in hybrid cars have recently been drawn again into policy debates as automakers have pressed the European Union to weaken CO₂ standards. A proposed ban on sales of new internal combustion cars in 2035 has faced intense pressure from the automotive sector and resistance from member states with significant car manufacturing.

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

An independent energy policy specialist, who was unaffiliated with the study, described the analysis a “highly valuable addition” after years in which parts of the car sector argued there was too little data to accurately assess actual emissions.

“The results demonstrate, without question, that the difference in official and real-world PHEV energy use and CO₂ output is much, much larger than for petrol or conventional vehicles,” the expert said. “All policy adjustments regarding PHEVs should be made with utmost caution and in the light of this evidence.”