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Plug-in hybrid electric vehicles release nearly 5x more planet-heating emissions than official figures show, according to a recent analysis.

Growing Discrepancy Between Official and Actual Emissions

Statistics shows that PHEVs release only 19% lower CO₂ than traditional gas and diesel vehicles, according to analysis carried out by a advocacy organization. That contrasts sharply with lab estimates, which assumed a 75% decrease in pollution.

Analysts examined data from onboard fuel consumption monitors of eight hundred thousand cars registered in the EU between 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, up from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported figures are falling,” said a senior researcher participating in the report. “That discrepancy is growing and poses a significant problem. Consequently, PHEVs emit nearly as much as gasoline vehicles.”

Primary Factors Driving the Emissions Gap

Analysts linked most of the gap to inflated estimates of the “utility factor” – the percentage of miles travelled in battery mode relative to overall distance. The team determined that just a quarter of travel was completed in EV mode, while official assumptions assumed 84%.

Even, when running in EV mode, pollution amounts were significantly higher than official projections. This happened because EV motors were insufficiently powerful enough to operate independently, leading to engines burning fossil fuels for almost a third of the travel covered in electric mode.

Regulatory and Financial Consequences

According to estimates, the underestimation of PHEV emissions allowed several major automaker companies to escape over €5bn in fines from 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would spend approximately €500 extra per year in running costs than would be estimated under laboratory conditions.

“The bold claims that automakers like to make about their PHEV cars are clearly way off the mark,” commented a automotive analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are only slightly better than standard petrol and diesel cars in terms of fuel use, CO₂ emissions, and running costs.”

Policy Discussion and Industry Lobbying

Hybrid cars have recently been brought again into policy debates as automakers have lobbied the EU to weaken CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced intense lobbying from the automotive sector and resistance from member states with large car manufacturing.

Several senior officials have proposed PHEVs as a possible “compromise” solution to include in the legislation.

One external energy economics specialist, who was not involved with the research, described the report a “highly valuable contribution” after years in which segments of the automotive sector argued there was insufficient data to properly evaluate actual emissions.

“These findings demonstrate, without question, that the gap between official and actual PHEV energy use and CO₂ output is much, much larger than for gasoline or diesel vehicles,” the expert said. “Any policy changes concerning PHEVs should be implemented with extreme caution and in the light of that data.”