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Plug-in hybrid electric vehicles emit almost 5x more planet-heating emissions than lab-reported figures show, as per a new analysis.

Growing Discrepancy Between Lab and Real-World Emissions

Statistics shows that PHEVs emit only one-fifth less CO₂ than conventional gas and diesel cars, according to analysis carried out by a non-profit organization. That contrasts sharply with lab tests, which assumed a 75% reduction in emissions.

Researchers studied information from onboard energy use monitors of eight hundred thousand vehicles registered in the EU between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official figures, up from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” said a senior analyst involved in the report. “This discrepancy is widening and poses a serious issue. As a result, PHEVs pollute nearly as much as gasoline cars.”

Key Reasons Behind the Discrepancy

Researchers attributed the majority of the gap to inflated estimates of the “electric driving share” – the ratio of miles travelled in battery mode relative to overall distance. The team determined that just 27% of travel was completed in EV mode, whereas lab assumptions suggested over four-fifths.

Even, when running in electric mode, pollution amounts were significantly higher than official projections. This happened because EV motors were insufficiently powerful sufficient to function independently, resulting to combustion motors using gasoline for nearly one-third of the distance covered in EV mode.

Regulatory and Economic Implications

Based on estimates, the lowballing of PHEV CO2 output allowed four major carmaker groups to avoid over €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs would pay approximately €500 extra annually in running expenses than is assumed under laboratory conditions.

“The bold claims that manufacturers like to make about their PHEV vehicles are obviously way off the mark,” stated a automotive analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel use, CO₂ production, and running costs.”

Policy Discussion and Industry Pressure

Hybrid cars have lately been drawn back into political debates as automakers have pressed the EU to weaken CO₂ targets. A proposed ban on sales of new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive industry and opposition from EU countries with significant car industries.

Several high-level politicians have proposed plug-in hybrids as a possible “compromise” solution to include in the legislation.

An external energy economics specialist, who was unaffiliated with the research, called the analysis a “highly valuable contribution” after years in which segments of the car sector argued there was too little data to properly evaluate real-world CO2 output.

“The results show, without question, that the gap in lab and actual PHEV energy use and CO₂ output is significantly greater than for petrol or diesel cars,” the expert stated. “All policy changes regarding PHEVs should be implemented with extreme caution and in the light of this evidence.”