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Plug-in hybrid electric vehicles emit almost 5x more planet-heating pollution than lab-reported figures indicate, according to a recent analysis.

Widening Gap In Lab and Actual Emissions

Data reveals that PHEVs release only one-fifth less CO₂ than traditional gas and diesel vehicles, based on research conducted by a non-profit organization. This differs sharply with laboratory tests, which suggested a three-quarters reduction in pollution.

Researchers studied data from in-vehicle energy use meters of 800,000 vehicles sold in the EU between 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, up from three and a half times in 2021.

“Actual emissions are rising, while lab-reported emissions are decreasing,” said a lead researcher involved in the study. “That gap is growing and creates a serious problem. As a result, PHEVs pollute almost as heavily as petrol cars.”

Primary Reasons Behind the Emissions Gap

Analysts linked the majority of the gap to overestimates of the “electric driving share” – the percentage of miles driven in electric power compared to total distance. The team determined that only 27% of travel was completed in EV mode, whereas official estimates assumed over four-fifths.

Additionally, when operating in electric mode, emission levels were well above official estimates. This happened because EV motors were insufficiently powerful enough to function alone, leading to engines using gasoline for almost a third of the travel covered in EV mode.

Regulatory and Financial Implications

According to calculations, the underestimation of PHEV emissions allowed several major carmaker groups to escape over €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs could pay about €500 more annually in operating expenses than is estimated under lab tests.

“The strong claims that manufacturers like to make about their PHEV vehicles are clearly far from the truth,” commented a automotive expert. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are only slightly better than standard petrol and diesel cars in terms of energy consumption, CO₂ emissions, and running expenses.”

Policy Discussion and Industry Pressure

Hybrid cars have lately been drawn again into political debates as automakers have lobbied the European Union to weaken CO₂ targets. A planned ban on new internal combustion vehicles in 2035 has faced intense pressure from the automotive sector and opposition from EU countries with large car manufacturing.

Some high-level officials have suggested PHEVs as a potential “compromise” option to introduce in the legislation.

One external energy economics expert, who was unaffiliated with the study, described the analysis a “very useful contribution” after a long period in which segments of the car industry argued there was insufficient information to accurately assess real-world emissions.

“These findings demonstrate, without question, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or diesel cars,” they said. “Any regulatory changes concerning PHEVs should be implemented with utmost caution and considering that evidence.”