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Plug-in hybrid cars emit nearly five times more planet-heating pollution than lab-reported figures indicate, as per a new report.

Widening Gap Between Lab and Real-World Emissions

Data shows that PHEVs release just one-fifth lower CO₂ than traditional petrol and diesel cars, based on research conducted by a advocacy group. That contrasts sharply with lab tests, which assumed a 75% decrease in emissions.

Analysts studied data from in-vehicle fuel consumption monitors of eight hundred thousand cars registered in the EU between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official figures, increased from 3.5 times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” stated a senior analyst involved in the report. “This gap is growing and poses a significant issue. Consequently, PHEVs emit almost as heavily as gasoline cars.”

Primary Reasons Driving the Emissions Gap

Analysts attributed the majority of the difference to overestimates of the “electric driving share” – the ratio of miles driven in battery mode relative to total mileage. They determined that only 27% of driving was done in EV mode, while lab estimates suggested over four-fifths.

Additionally, when running in electric mode, emission amounts were significantly higher than official projections. This happened because electric motors were insufficiently powerful sufficient to function alone, resulting to engines using fossil fuels for nearly one-third of the distance covered in EV mode.

Regulatory and Economic Implications

According to estimates, the underestimation of PHEV emissions allowed four large carmaker companies to escape over €5bn in fines between 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs would pay approximately €500 extra annually in operating costs than would be assumed under laboratory tests.

“The bold statements that manufacturers often promote about their PHEV cars are obviously way off the mark,” stated a automotive expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are only slightly better than regular gas and diesel vehicles in terms of fuel consumption, CO₂ production, and running costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid vehicles have lately been drawn again into policy debates as carmakers have lobbied the European Union to weaken CO₂ standards. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced heavy lobbying from the car industry and opposition from member states with significant automotive industries.

Some senior officials have suggested plug-in hybrids as a potential “flexibility” solution to include in the legislation.

One independent energy economics specialist, who was unaffiliated with the study, called the analysis a “highly valuable addition” after years in which segments of the automotive industry claimed there was insufficient data to properly assess real-world emissions.

“These findings demonstrate, beyond any doubt, that the difference in lab and real-world PHEV energy use and CO₂ emissions is significantly greater than for petrol or conventional vehicles,” they stated. “Any regulatory adjustments regarding PHEVs should be made with utmost care and considering this evidence.”