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PHEVs emit nearly 5x greater global warming emissions than lab-reported figures show, according to a new analysis.

Growing Discrepancy Between Lab and Real-World CO2 Output

Data shows that PHEVs emit just 19% lower CO₂ than conventional gas and diesel vehicles, based on analysis carried out by a non-profit group. This differs significantly with laboratory tests, which suggested a 75% decrease in emissions.

Researchers examined information from in-vehicle fuel consumption monitors of 800,000 vehicles sold in the EU between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while official figures are decreasing,” said a lead analyst participating in the study. “This discrepancy is growing and poses a serious problem. Consequently, PHEVs pollute almost as much as gasoline cars.”

Key Reasons Behind the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in electric mode relative to overall mileage. The team found that only a quarter of travel was done in EV mode, while official estimates assumed over four-fifths.

Even, when running in EV mode, pollution amounts were well above official projections. This happened because electric motors were insufficiently powerful sufficient to operate alone, resulting to combustion motors using fossil fuels for almost a third of the distance covered in EV mode.

Policy and Economic Implications

Based on estimates, the lowballing of PHEV emissions allowed several major automaker companies to avoid more than €5bn in fines from 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs would pay approximately €500 more annually in operating expenses than is estimated under laboratory conditions.

“The bold statements that automakers like to make about their plug-in hybrid cars are obviously far from the mark,” commented a transport expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are little better than standard gas and diesel cars in terms of energy consumption, CO₂ production, and running costs.”

Political Debate and Industry Lobbying

Hybrid cars have lately been drawn back into political debates as automakers have lobbied the European Union to relax CO₂ standards. A proposed prohibition on new combustion engine cars in 2035 has faced heavy pressure from the car industry and resistance from member states with large car manufacturing.

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

One independent energy economics specialist, who was not involved with the study, called the report a “very useful addition” after years in which segments of the automotive industry argued there was too little data to accurately assess real-world CO2 output.

“These findings show, without question, that the gap in lab and actual PHEV energy use and CO₂ emissions is much, much larger than for petrol or diesel vehicles,” they said. “Any policy adjustments concerning PHEVs should be made with extreme care and in the light of this evidence.”