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Plug-in hybrid cars produce nearly 5x greater planet-heating pollution than official data show, as per a recent report.

Growing Discrepancy In Lab and Real-World Emissions

Data reveals that PHEVs emit only 19% less CO₂ than traditional gas and diesel cars, according to research carried out by a advocacy group. This differs sharply with lab tests, which suggested a three-quarters decrease in pollution.

Analysts examined data from in-vehicle energy use meters of eight hundred thousand vehicles sold in Europe from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported figures are falling,” stated a senior analyst participating in the study. “This discrepancy is growing and poses a significant issue. Consequently, PHEVs pollute nearly as heavily as gasoline cars.”

Key Reasons Driving the Emissions Gap

Researchers linked most of the difference to inflated estimates of the “electric driving share” – the ratio of miles travelled in electric power relative to total distance. They found that only a quarter of driving was completed in EV mode, while official estimates assumed 84%.

Even, when running in electric mode, emission levels were significantly higher than official estimates. This happened because electric motors were not strong sufficient to operate independently, leading to engines burning gasoline for almost one-third of the travel covered in electric mode.

Policy and Financial Implications

Based on calculations, the underestimation of PHEV CO2 output enabled several major carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs could pay about €500 more per year in running costs than would be estimated under lab conditions.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are clearly far from the mark,” commented a automotive analyst. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and running costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid cars have lately been brought back into policy debates as carmakers have pressed the EU to relax CO₂ targets. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the automotive industry and opposition from member states with large automotive industries.

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

One external energy policy specialist, who was not involved with the research, called the analysis a “highly valuable contribution” after a long period in which segments of the car sector claimed there was insufficient information to accurately assess real-world emissions.

“The results show, without question, that the gap between lab and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or diesel vehicles,” they stated. “All policy changes concerning PHEVs should be made with utmost caution and in the light of this data.”