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Plug-in hybrid electric vehicles release nearly five times greater global warming pollution than official data show, as per a new analysis.

Widening Discrepancy Between Official and Actual CO2 Output

Data shows that PHEVs emit only one-fifth lower CO₂ than conventional petrol and diesel cars, according to research carried out by a non-profit organization. This differs significantly with lab estimates, which suggested a three-quarters reduction in pollution.

Analysts examined data from in-vehicle fuel consumption monitors of eight hundred thousand cars registered in Europe between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, increased from three and a half times in 2021.

“Real-world emissions are increasing, while official emissions are falling,” stated a senior researcher participating in the report. “That gap is widening and poses a serious problem. Consequently, PHEVs pollute nearly as much as petrol vehicles.”

Key Factors Behind the Emissions Gap

Researchers linked the majority of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in electric power compared to overall distance. The team found that just a quarter of driving was done in electric mode, while lab estimates assumed 84%.

Additionally, when running in electric mode, emission amounts were significantly higher than official estimates. This occurred because EV motors were not strong enough to operate alone, leading to engines burning gasoline for almost one-third of the travel completed in electric mode.

Policy and Financial Consequences

According to calculations, the lowballing of PHEV CO2 output enabled four major automaker companies to avoid over €5bn in fines from 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ standards.

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

“The bold statements that manufacturers often promote about their plug-in hybrid cars are clearly way off the mark,” commented a automotive analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are little improved than regular gas and diesel cars in terms of energy consumption, CO₂ emissions, and running expenses.”

Policy Debate and Automotive Pressure

Hybrid vehicles have lately been brought back into policy discussions as automakers have lobbied the European Union to weaken CO₂ targets. A planned prohibition on sales of new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and opposition from member states with large car industries.

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

One independent energy policy expert, who was not involved with the research, called the report a “highly valuable contribution” after years in which segments of the car industry claimed there was insufficient data to accurately assess real-world emissions.

“The results show, beyond any doubt, that the difference in official and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel vehicles,” they stated. “All policy changes regarding PHEVs should be implemented with utmost caution and in the light of that evidence.”