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PHEVs emit nearly 5x greater global warming emissions than official data show, as per a new report.

Growing Discrepancy In Lab and Actual CO2 Output

Data shows that PHEVs emit only 19% lower CO₂ than conventional petrol and diesel cars, based on research conducted by a non-profit organization. This differs significantly with laboratory tests, which assumed a three-quarters reduction in emissions.

Analysts studied information from in-vehicle energy use meters of 800,000 vehicles registered in the EU from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, up from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are decreasing,” said a lead researcher participating in the study. “This gap is widening and poses a significant issue. As a result, PHEVs emit nearly as much as gasoline cars.”

Key Factors Driving the Discrepancy

Researchers linked most of the difference to overestimates of the “electric driving share” – the ratio of kilometers travelled in battery power relative to total mileage. They found that only a quarter of driving was completed in electric mode, while lab assumptions suggested 84%.

Even, when running in electric mode, emission amounts were significantly higher than lab projections. This occurred because electric motors were not strong sufficient to function alone, resulting to engines using gasoline for almost one-third of the distance covered in EV mode.

Regulatory and Economic Implications

Based on estimates, the underestimation of PHEV CO2 output allowed several large 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 would pay about €500 more per year in operating expenses than would be assumed under lab tests.

“The strong statements that manufacturers often promote about their PHEV vehicles are clearly way off the mark,” commented a automotive expert. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of fuel use, CO₂ production, and running costs.”

Political Debate and Automotive Pressure

Hybrid cars have lately been drawn again into policy discussions as carmakers have lobbied the EU to relax CO₂ targets. A proposed prohibition on sales of new combustion engine cars in 2035 has faced intense pressure from the automotive industry and opposition from member states with significant car manufacturing.

Several senior officials have proposed plug-in hybrids as a possible “compromise” solution to include in the legislation.

One external energy economics expert, who was not involved with the study, called the report a “highly valuable addition” after years in which segments of the car industry argued there was too little data to accurately evaluate real-world CO2 output.

“The results show, beyond any doubt, that the gap between lab and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional cars,” the expert stated. “All regulatory changes regarding PHEVs should be made with extreme care and in the light of this data.”