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Plug-in hybrid cars produce nearly five times greater global warming pollution than official figures show, according to a recent report.

Widening Gap Between Lab and Real-World Emissions

Data reveals that PHEVs emit just one-fifth less CO₂ than traditional petrol and diesel cars, based on research conducted by a non-profit group. This contrasts sharply with laboratory estimates, which assumed a three-quarters decrease in emissions.

Researchers examined data from in-vehicle fuel consumption meters of eight hundred thousand cars 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 lab estimates, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are decreasing,” said a senior analyst participating in the report. “That discrepancy is widening and creates a significant issue. Consequently, PHEVs emit almost as much as gasoline cars.”

Key Factors Driving the Discrepancy

Analysts attributed most of the gap to inflated estimates of the “utility factor” – the ratio of kilometers travelled in electric power relative to overall distance. The team found that only a quarter of driving was done in electric mode, while official estimates assumed over four-fifths.

Even, when running in EV mode, emission levels were well above official estimates. That happened because electric motors were insufficiently powerful enough to function alone, resulting to combustion motors burning fossil fuels for almost a third of the distance completed in EV mode.

Policy and Financial Consequences

Based on estimates, the lowballing of PHEV emissions enabled several major automaker groups to escape more than €5bn in penalties between 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs could spend about €500 more per year in operating expenses than is assumed under laboratory conditions.

“The strong claims that automakers like to make about their plug-in hybrid vehicles are clearly way off the mark,” commented a transport expert. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are only slightly improved than standard gas and diesel cars in terms of energy use, CO₂ production, and running expenses.”

Political Discussion and Industry Pressure

Hybrid cars have recently been brought back into policy debates as carmakers have pressed the European Union to relax CO₂ targets. A planned ban on new internal combustion cars in 2035 has faced intense pressure from the car industry and opposition from EU countries with significant car manufacturing.

Several high-level officials have proposed PHEVs as a potential “flexibility” option to include in the regulation.

One external energy economics expert, who was unaffiliated with the study, described the analysis a “highly valuable contribution” after years in which parts of the automotive industry argued there was insufficient information to accurately evaluate real-world CO2 output.

“The results demonstrate, without question, that the difference between official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or diesel cars,” the expert stated. “Any regulatory changes regarding PHEVs should be implemented with utmost caution and considering this data.”