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Plug-in hybrid electric vehicles emit almost five times more planet-heating pollution than lab-reported figures show, according to a recent analysis.

Widening Gap In Lab and Real-World CO2 Output

Data shows that PHEVs release just 19% less CO₂ than conventional gas and diesel cars, based on analysis carried out by a advocacy organization. This contrasts significantly with laboratory estimates, which assumed a 75% reduction in pollution.

Researchers examined information from in-vehicle fuel consumption meters of 800,000 vehicles sold in Europe between 2021 and 2023. The team discovered that actual CO₂ emissions 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 decreasing,” stated a lead researcher involved in the report. “That discrepancy is growing and creates a significant problem. Consequently, PHEVs pollute nearly as heavily as petrol cars.”

Key Reasons Behind the Discrepancy

Analysts attributed most of the gap to overestimates of the “electric driving share” – the ratio of kilometers driven in electric mode compared to total distance. They found that just a quarter of travel was completed in EV mode, while official assumptions assumed over four-fifths.

Even, when running in electric mode, pollution levels were significantly higher than official estimates. This occurred because electric motors were insufficiently powerful enough to operate alone, resulting to engines burning gasoline for almost one-third of the distance covered in EV mode.

Regulatory and Financial Implications

According to calculations, the lowballing of PHEV CO2 output enabled four major carmaker companies to escape more than €5bn in fines from 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ standards.

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

“The strong statements that automakers often promote about their PHEV cars are obviously way off the truth,” commented a transport expert. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the planet and cutting money. In reality, PHEVs are only slightly improved than regular gas and diesel cars in terms of fuel use, CO₂ production, and operating expenses.”

Policy Debate and Automotive Lobbying

Plug-in hybrid cars have lately been brought back into policy debates as carmakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced intense pressure from the car industry and opposition from EU countries with significant automotive industries.

Several senior politicians have suggested PHEVs as a potential “compromise” option to include in the legislation.

One independent energy economics specialist, who was unaffiliated with the research, called the report a “very useful addition” after years in which segments of the car sector argued there was insufficient information to accurately evaluate real-world CO2 output.

“The results show, beyond any doubt, that the difference between official and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel vehicles,” they stated. “Any regulatory changes regarding PHEVs should be made with extreme caution and in the light of that evidence.”