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Plug-in hybrid cars release nearly five times greater global warming pollution than lab-reported figures indicate, as per a new report.

Widening Discrepancy Between Official and Actual Emissions

Statistics reveals that PHEVs release just 19% lower CO₂ than conventional petrol and diesel vehicles, based on analysis carried out by a non-profit organization. This contrasts sharply with lab tests, which suggested a three-quarters reduction in emissions.

Analysts examined data from in-vehicle fuel consumption meters of 800,000 cars registered in Europe between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official emissions are falling,” said a senior researcher participating in the study. “That discrepancy is growing and creates a significant issue. As a result, PHEVs emit nearly as much as gasoline cars.”

Primary Reasons Driving the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “utility factor” – the percentage of miles travelled in battery power relative to overall mileage. They found that only a quarter of driving was done in EV mode, while official assumptions suggested over four-fifths.

Even, when operating in EV mode, emission amounts were well above lab estimates. This happened because EV motors were not strong enough to function alone, leading to combustion motors using fossil fuels for almost one-third of the travel covered in EV mode.

Regulatory and Financial Consequences

According to calculations, the underestimation of PHEV emissions allowed several large automaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs could pay approximately €500 extra per year in running expenses than is assumed under lab tests.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are obviously way off the truth,” commented a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are little improved than standard petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating expenses.”

Policy Discussion and Automotive Lobbying

Hybrid vehicles have lately been brought back into policy debates as automakers have pressed the European Union to weaken CO₂ standards. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the automotive industry and resistance from member states with large automotive manufacturing.

Several high-level officials have proposed plug-in hybrids as a possible “compromise” solution to introduce in the legislation.

An independent energy economics expert, who was unaffiliated with the research, described the analysis a “very useful contribution” after years in which segments of the car sector argued there was insufficient data to accurately assess actual CO2 output.

“The results show, beyond any doubt, that the difference between lab and real-world PHEV energy use and CO₂ emissions is significantly larger than for petrol or diesel vehicles,” they said. “All regulatory adjustments regarding PHEVs should be implemented with utmost care and in the light of that evidence.”