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Plug-in hybrid electric vehicles release almost 5x more global warming pollution than lab-reported data indicate, as per a new analysis.

Widening Discrepancy In Official and Actual Emissions

Data shows that PHEVs emit just 19% lower CO₂ than conventional petrol and diesel vehicles, based on research conducted by a non-profit organization. This differs significantly with laboratory tests, which assumed a 75% decrease in pollution.

Analysts examined data from onboard energy use monitors of eight hundred thousand vehicles sold in Europe from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while official figures are decreasing,” stated a lead analyst participating in the study. “This gap is widening and creates a serious problem. As a result, PHEVs emit almost as heavily as gasoline vehicles.”

Key Factors Driving the Emissions Gap

Analysts attributed the majority of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in electric mode compared to overall distance. They determined that only 27% of driving was done in EV mode, while lab estimates suggested over four-fifths.

Even, when running in EV mode, emission levels were significantly higher than official estimates. This happened because electric motors were not strong sufficient to function independently, resulting to engines using gasoline for nearly 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 groups to avoid over €5bn in fines from 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ targets.

Additionally, owners of PHEVs could pay approximately €500 extra annually in operating costs than is assumed under laboratory conditions.

“The strong claims that automakers like to make about their plug-in hybrid cars are clearly way off the mark,” stated a automotive analyst. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are little improved than standard gas and diesel vehicles in terms of fuel use, CO₂ emissions, and running costs.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have recently been drawn back into political discussions as automakers have pressed the European Union to weaken CO₂ targets. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with significant automotive manufacturing.

Several high-level officials have suggested plug-in hybrids as a possible “flexibility” option to introduce in the regulation.

An independent energy policy expert, who was unaffiliated with the research, called the analysis a “very useful contribution” after a long period in which parts of the automotive industry argued there was insufficient data to accurately assess actual emissions.

“The results demonstrate, beyond any doubt, that the difference between lab and real-world PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or conventional vehicles,” they said. “Any regulatory adjustments concerning PHEVs should be made with extreme caution and considering that evidence.”