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Plug-in hybrid electric vehicles release almost five times more global warming emissions than lab-reported data indicate, according to a recent report.

Growing Gap In Official and Actual Emissions

Statistics reveals that PHEVs emit just one-fifth less CO₂ than conventional petrol and diesel vehicles, based on research conducted by a advocacy group. This differs sharply with lab tests, which suggested a 75% decrease in pollution.

Analysts examined data from onboard energy use monitors of 800,000 vehicles registered in Europe between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while official figures are falling,” stated a lead analyst participating in the study. “That gap is widening and creates a significant issue. Consequently, PHEVs pollute almost as much as petrol cars.”

Primary Factors Behind the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “electric driving share” – the ratio of miles travelled in battery power relative to total distance. They determined that only 27% of travel was completed in EV mode, while lab assumptions assumed 84%.

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

Policy and Financial Implications

According to calculations, the lowballing of PHEV CO2 output enabled four major automaker companies to avoid more than €5bn in penalties from 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs could pay approximately €500 more per year in running costs than is estimated under laboratory tests.

“The bold claims that manufacturers often promote about their PHEV cars are obviously way off the truth,” commented a automotive expert. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running costs.”

Policy Debate and Industry Lobbying

Hybrid cars have recently been drawn back into political discussions as automakers have lobbied the European Union to weaken CO₂ standards. A proposed ban on sales of new combustion engine cars in 2035 has faced intense lobbying from the automotive sector and opposition from member states with large car industries.

Several high-level politicians have suggested PHEVs as a possible “compromise” solution to introduce in the legislation.

An external energy policy expert, who was not involved with the research, described the analysis a “highly valuable addition” after years in which parts of the automotive industry claimed there was insufficient data to properly evaluate actual emissions.

“The results show, without question, that the gap between official and actual PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or diesel cars,” they stated. “All policy changes regarding PHEVs should be made with utmost care and in the light of that data.”