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Plug-in hybrid cars produce nearly 5x more global warming emissions than official figures indicate, according to a new analysis.

Widening Gap Between Official and Real-World CO2 Output

Data reveals that PHEVs release only one-fifth less CO₂ than traditional gas and diesel cars, according to research carried out by a advocacy organization. This differs sharply with laboratory estimates, which suggested a 75% reduction in emissions.

Analysts examined information from in-vehicle fuel consumption meters of eight hundred thousand vehicles registered in Europe from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are decreasing,” stated a senior researcher participating in the study. “That discrepancy is widening and creates a significant issue. As a result, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Reasons Driving the Discrepancy

Analysts attributed the majority of the gap to inflated estimates of the “electric driving share” – the ratio of miles travelled in electric power compared to overall distance. The team determined that just a quarter of driving was done in electric mode, whereas official estimates suggested over four-fifths.

Even, when running in EV mode, pollution levels were significantly higher than lab projections. That happened because EV motors were not strong sufficient to operate independently, resulting to engines burning gasoline for almost one-third of the distance completed in EV mode.

Policy and Financial Consequences

According to calculations, the underestimation of PHEV emissions allowed four large automaker companies to escape over €5bn in fines between 2021 and 2023, by artificially simplifying compliance with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs would spend approximately €500 more per year in running expenses than is estimated under laboratory conditions.

“The bold claims that manufacturers often promote about their PHEV vehicles are obviously far from the truth,” stated a transport expert. “Buyers are being duped into believing that by buying a PHEV, they are helping the planet and saving money. Actually, PHEVs are little improved than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Policy Discussion and Automotive Pressure

Hybrid vehicles have lately been drawn again into policy debates as automakers have pressed the EU to weaken CO₂ standards. A proposed prohibition on new combustion engine cars in 2035 has faced intense pressure from the car industry and resistance from EU countries with significant automotive manufacturing.

Several senior officials have suggested PHEVs as a possible “flexibility” option to include in the legislation.

One independent energy economics specialist, who was unaffiliated with the research, called the analysis a “highly valuable contribution” after a long period in which segments of the car industry claimed there was insufficient data to accurately assess real-world emissions.

“The results demonstrate, beyond any doubt, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or conventional cars,” they stated. “All regulatory adjustments regarding PHEVs should be implemented with utmost caution and considering that evidence.”