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PHEVs emit nearly five times greater global warming emissions than lab-reported data indicate, as per a new analysis.

Growing Gap In Official and Real-World Emissions

Data reveals that PHEVs emit only one-fifth lower CO₂ than traditional gas and diesel cars, according to research carried out by a non-profit organization. This contrasts sharply with lab estimates, which assumed a 75% decrease in emissions.

Researchers examined information from in-vehicle fuel consumption monitors of 800,000 vehicles sold in the EU from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, up from three and a half times in 2021.

“Actual CO2 output are increasing, while official emissions are decreasing,” stated a lead researcher involved in the report. “This gap is widening and creates a serious problem. As a result, PHEVs emit almost as heavily as petrol cars.”

Key Reasons Behind the Discrepancy

Researchers attributed most of the gap to overestimates of the “utility factor” – the ratio of kilometers travelled in electric mode compared to total distance. They determined that just a quarter of travel was done in EV mode, while official estimates suggested over four-fifths.

Additionally, when operating in electric mode, emission levels were well above lab projections. That happened because electric motors were insufficiently powerful sufficient to operate independently, resulting to engines using gasoline for almost one-third of the distance covered in EV mode.

Policy and Financial Implications

According to estimates, the underestimation of PHEV emissions allowed several large automaker companies to escape more than €5bn in penalties between 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs could spend about €500 more per year in running expenses than would be estimated under lab tests.

“The strong claims that automakers like to make about their plug-in hybrid vehicles are clearly far from the truth,” stated a transport analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the planet and saving money. In reality, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel use, CO₂ emissions, and operating costs.”

Political Debate and Automotive Lobbying

Hybrid vehicles have recently been brought back into policy discussions as carmakers have lobbied the European Union to relax CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced intense lobbying from the car industry and resistance from member states with large car industries.

Some high-level politicians have suggested plug-in hybrids as a potential “compromise” solution to include in the legislation.

An external energy policy specialist, who was not involved with the study, described the analysis a “highly valuable addition” after a long period in which parts of the automotive sector claimed there was too little information to accurately evaluate real-world CO2 output.

“The results demonstrate, without question, that the difference between lab and real-world PHEV energy use and CO₂ output is significantly larger than for petrol or conventional vehicles,” they said. “Any policy adjustments regarding PHEVs should be made with extreme caution and in the light of this data.”