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Plug-in hybrid cars release almost 5x greater planet-heating pollution than official data indicate, as per a recent report.

Growing Gap In Official and Actual Emissions

Data shows that PHEVs emit only one-fifth lower CO₂ than conventional gas and diesel cars, based on research conducted by a advocacy organization. That differs sharply with laboratory estimates, which assumed a three-quarters decrease in emissions.

Analysts studied information from onboard energy use monitors of eight hundred thousand vehicles registered in Europe between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported figures are falling,” stated a lead researcher participating in the report. “That discrepancy is widening and poses a significant issue. Consequently, PHEVs emit almost as much as gasoline vehicles.”

Primary Reasons Driving the Discrepancy

Analysts attributed the majority of the gap to inflated estimates of the “utility factor” – the ratio of kilometers driven in battery power relative to overall mileage. They determined that just a quarter of driving was done in electric mode, whereas lab assumptions assumed 84%.

Additionally, when running in EV mode, pollution amounts were significantly higher than official projections. That occurred because electric motors were insufficiently powerful enough to operate independently, leading to engines using fossil fuels for almost a third of the distance covered in EV mode.

Policy and Economic Consequences

Based on calculations, the underestimation of PHEV emissions allowed four large automaker groups to escape over €5bn in fines between 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ standards.

Additionally, drivers of PHEVs could pay approximately €500 more annually in running costs than would be assumed under lab conditions.

“The strong claims that manufacturers often promote about their plug-in hybrid cars are clearly far from the truth,” commented a automotive expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are only slightly better than standard petrol and diesel vehicles in terms of energy use, CO₂ emissions, and running expenses.”

Political Debate and Industry Pressure

Hybrid cars have lately been drawn again into policy discussions as carmakers have pressed the European Union to weaken CO₂ standards. A planned prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the automotive industry and opposition from EU countries with large car industries.

Several high-level politicians have proposed PHEVs as a possible “compromise” option to include in the legislation.

An external energy economics specialist, who was not involved with the research, described the analysis a “highly valuable addition” after a long period in which segments of the car industry argued there was too little information to accurately assess actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference between lab and actual PHEV energy use and CO₂ output is much, much larger than for petrol or diesel cars,” the expert stated. “Any policy changes concerning PHEVs should be made with extreme care and considering this data.”