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PHEVs release almost 5x greater planet-heating emissions than official figures indicate, according to a recent analysis.

Growing Gap In Lab and Real-World CO2 Output

Data shows that PHEVs release only 19% less CO₂ than traditional petrol and diesel vehicles, based on research conducted by a advocacy group. That differs sharply with lab tests, which assumed a three-quarters reduction in pollution.

Researchers studied information from in-vehicle energy use meters of 800,000 cars registered in the EU between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official estimates, up from three and a half times in 2021.

“Real-world emissions are rising, while official emissions are decreasing,” said a lead researcher involved in the report. “That discrepancy is widening and creates a serious issue. As a result, PHEVs pollute almost as much as gasoline vehicles.”

Primary Reasons Driving the Emissions Gap

Researchers attributed most of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers driven in battery power compared to total distance. They found that only 27% of travel was completed in EV mode, while official assumptions assumed over four-fifths.

Additionally, when running in electric mode, emission levels were well above official estimates. This happened because electric motors were insufficiently powerful enough to function independently, resulting to engines burning fossil fuels for nearly one-third of the distance completed in EV mode.

Policy and Economic Implications

According to estimates, the underestimation of PHEV CO2 output enabled several large automaker groups to escape over €5bn in fines between 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs would spend about €500 extra per year in operating costs than would be estimated under laboratory conditions.

“The strong claims that manufacturers like to make about their PHEV cars are clearly way off the mark,” commented a transport expert. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and saving money. In reality, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy use, CO₂ production, and running costs.”

Political Debate and Industry Lobbying

Hybrid vehicles have lately been brought back into political discussions as automakers have pressed the European Union to weaken CO₂ targets. A planned prohibition on new combustion engine cars in 2035 has faced intense lobbying from the car sector and resistance from EU countries with significant automotive manufacturing.

Several senior officials have suggested PHEVs as a possible “compromise” solution to introduce in the legislation.

An independent energy economics expert, who was not involved with the study, described the analysis a “highly valuable addition” after a long period in which parts of the car industry argued there was insufficient data to accurately evaluate real-world CO2 output.

“These findings demonstrate, without question, that the difference between official and real-world PHEV energy use and CO₂ emissions is significantly larger than for gasoline or diesel vehicles,” they said. “Any policy changes regarding PHEVs should be made with extreme care and considering that evidence.”