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Plug-in hybrid electric vehicles release nearly five times greater global warming emissions than lab-reported figures indicate, as per a recent report.

Widening Gap In Official and Real-World CO2 Output

Statistics shows that PHEVs emit only one-fifth lower CO₂ than conventional petrol and diesel cars, based on research carried out by a non-profit group. This differs significantly with laboratory tests, which assumed a 75% decrease in emissions.

Analysts studied information from in-vehicle energy use meters of eight hundred thousand cars sold in the EU from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, increased from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported figures are falling,” stated a senior researcher participating in the report. “That gap is widening and poses a serious problem. Consequently, PHEVs emit almost as heavily as petrol cars.”

Primary Factors Driving the Discrepancy

Researchers attributed most of the gap to overestimates of the “utility factor” – the percentage of kilometers travelled in battery mode compared to total mileage. The team found that only 27% of driving was done in electric mode, while lab assumptions suggested over four-fifths.

Even, when operating in EV mode, emission levels were significantly higher than official estimates. That occurred because electric motors were not strong sufficient to operate alone, leading to combustion motors burning gasoline for nearly a third of the distance covered in electric mode.

Policy and Financial Consequences

Based on calculations, the lowballing of PHEV emissions enabled four major carmaker companies to avoid over €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs would spend about €500 extra per year in operating expenses than would be assumed under laboratory conditions.

“The strong claims that automakers often promote about their PHEV cars are clearly far from the mark,” commented a transport analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving costs. In reality, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and running costs.”

Political Debate and Automotive Pressure

Plug-in hybrid cars have lately been brought back into policy debates as automakers have pressed the European Union to relax CO₂ standards. A planned ban on new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and opposition from EU countries with large automotive industries.

Several high-level politicians have proposed PHEVs as a possible “compromise” solution to introduce in the regulation.

An external energy economics specialist, who was not involved with the study, called the report a “highly valuable addition” after years in which segments of the car sector claimed there was too little information to properly evaluate actual CO2 output.

“These findings show, without question, that the gap between lab and actual PHEV energy use and CO₂ emissions is much, much greater than for gasoline or conventional vehicles,” the expert said. “All policy adjustments concerning PHEVs should be implemented with extreme caution and in the light of that data.”