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Plug-in hybrid electric vehicles release nearly 5x greater planet-heating pollution than lab-reported figures show, as per a new report.

Growing Gap Between Official and Real-World Emissions

Statistics shows that PHEVs release only 19% lower CO₂ than conventional petrol and diesel vehicles, based on analysis conducted by a non-profit organization. This differs sharply with laboratory tests, which assumed a 75% reduction in pollution.

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

“Actual emissions are rising, while official emissions are falling,” stated a senior analyst involved in the report. “This gap is growing and creates a serious issue. As a result, PHEVs emit almost as much as gasoline cars.”

Primary Reasons Behind the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric mode relative to total distance. The team found that only a quarter of driving was done in electric mode, whereas lab assumptions assumed over four-fifths.

Additionally, when running in electric mode, pollution amounts were well above official projections. This occurred because EV motors were insufficiently powerful enough to operate alone, leading to combustion motors burning fossil fuels for almost one-third of the distance completed in EV mode.

Policy and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output enabled four major automaker groups to escape over €5bn in fines from 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs would spend approximately €500 more annually in running costs than is assumed under lab tests.

“The strong statements that automakers like to make about their PHEV vehicles are obviously far from the mark,” commented a automotive analyst. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating expenses.”

Policy Debate and Automotive Pressure

Plug-in hybrid vehicles have lately been drawn again into political debates as carmakers have pressed the European Union to weaken CO₂ standards. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive industry and opposition from EU countries with large car industries.

Some senior politicians have proposed PHEVs as a potential “compromise” option to include in the regulation.

An external energy economics expert, who was unaffiliated with the study, called the analysis a “highly valuable addition” after years in which parts of the car industry claimed there was insufficient data to properly evaluate actual emissions.

“These findings demonstrate, without question, that the difference between lab and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or diesel cars,” they said. “All regulatory changes concerning PHEVs should be made with extreme care and in the light of this data.”