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PHEVs release almost 5x greater planet-heating pollution than official data indicate, as per a recent report.

Growing Gap Between Official and Real-World CO2 Output

Data shows that PHEVs release just 19% less CO₂ than conventional petrol and diesel cars, according to research conducted by a advocacy organization. That differs significantly with laboratory tests, which suggested a 75% decrease in pollution.

Analysts examined data from in-vehicle fuel consumption meters of eight hundred thousand vehicles registered in the EU from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while official emissions are decreasing,” said a lead researcher involved in the report. “This gap is widening and poses a significant problem. As a result, PHEVs pollute nearly as heavily as gasoline cars.”

Key Factors Driving the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “electric driving share” – the ratio of miles travelled in electric power relative to total mileage. They found that just a quarter of driving was done in electric mode, while official assumptions suggested 84%.

Additionally, when operating in electric mode, pollution levels were significantly higher than lab projections. This occurred because EV motors were insufficiently powerful sufficient to operate independently, resulting to engines using fossil fuels for nearly one-third of the distance completed in EV mode.

Policy and Financial Consequences

According to calculations, the underestimation of PHEV CO2 output allowed four major automaker companies to escape more than €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs could spend approximately €500 more per year in running expenses than would be assumed under lab conditions.

“The strong statements that automakers often promote about their PHEV cars are clearly way off the truth,” commented a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel consumption, CO₂ production, and running costs.”

Policy Debate and Industry Pressure

Plug-in hybrid cars have recently been brought back into policy debates as automakers have lobbied the EU to relax CO₂ targets. A planned prohibition on new combustion engine vehicles in 2035 has faced heavy lobbying from the car industry and resistance from EU countries with significant automotive industries.

Some high-level politicians have suggested PHEVs as a possible “flexibility” option to introduce in the legislation.

An independent energy policy expert, who was not involved with the research, called the analysis a “very useful contribution” after a long period in which parts of the car sector claimed there was too little information to accurately assess actual CO2 output.

“The results demonstrate, without question, that the difference in lab and real-world PHEV energy use and CO₂ emissions is much, much greater than for petrol or conventional cars,” they said. “All policy adjustments regarding PHEVs should be made with extreme caution and considering that evidence.”