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Plug-in hybrid cars release almost five times greater planet-heating emissions than official figures indicate, as per a new report.

Growing Gap In Official and Actual CO2 Output

Statistics shows that PHEVs emit just 19% lower CO₂ than traditional gas and diesel vehicles, based on analysis conducted by a advocacy group. This contrasts sharply with lab estimates, which suggested a three-quarters reduction in pollution.

Researchers examined information from onboard energy use meters of eight hundred thousand cars registered in Europe between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, up from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported emissions are falling,” said a senior analyst involved in the report. “This discrepancy is widening and creates a serious problem. Consequently, PHEVs pollute almost as much as gasoline vehicles.”

Key Factors Behind the Discrepancy

Analysts linked most of the difference to inflated estimates of the “utility factor” – the percentage of miles travelled in electric mode compared to total mileage. They determined that just a quarter of travel was completed in EV mode, whereas lab assumptions assumed over four-fifths.

Additionally, when running in EV mode, emission levels were well above lab projections. This occurred because EV motors were insufficiently powerful enough to operate independently, resulting to combustion motors burning gasoline for almost one-third of the travel covered in EV mode.

Policy and Financial Implications

According to estimates, the underestimation of PHEV CO2 output allowed four large carmaker groups to avoid over €5bn in penalties from 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ standards.

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

“The strong claims that automakers often promote about their PHEV vehicles are obviously far from the mark,” commented a transport expert. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are only slightly better than standard gas and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Discussion and Industry Pressure

Hybrid vehicles have recently been brought again into political debates as automakers have lobbied the EU to relax CO₂ targets. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced intense pressure from the car industry and resistance from member states with large automotive industries.

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

One external energy economics expert, who was not involved with the research, called the report a “highly valuable contribution” after a long period in which segments of the automotive sector argued there was insufficient data to properly evaluate real-world emissions.

“These findings demonstrate, without question, that the difference in official and real-world PHEV energy use and CO₂ output is much, much larger than for gasoline or diesel cars,” the expert stated. “All policy changes concerning PHEVs should be made with utmost caution and in the light of that evidence.”