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Plug-in hybrid electric vehicles produce nearly five times more planet-heating emissions than official figures indicate, according to a recent report.

Growing Discrepancy Between Lab and Actual CO2 Output

Data reveals that PHEVs emit only 19% lower CO₂ than conventional petrol and diesel vehicles, based on analysis conducted by a non-profit organization. This differs sharply with lab tests, which suggested a 75% reduction in pollution.

Researchers examined data from onboard fuel consumption meters of eight hundred thousand cars registered in the EU between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, increased from three and a half times in 2021.

“Actual emissions are rising, while lab-reported emissions are decreasing,” said a lead analyst participating in the report. “That discrepancy is growing and creates a significant issue. Consequently, PHEVs pollute nearly as much as gasoline vehicles.”

Primary Factors Driving the Emissions Gap

Analysts linked most of the difference to overestimates of the “electric driving share” – the percentage of miles travelled in electric mode compared to total mileage. They found that only a quarter of travel was completed in EV mode, while official estimates assumed 84%.

Even, when operating in EV mode, emission amounts were well above official projections. This occurred because electric motors were insufficiently powerful sufficient to operate alone, leading to combustion motors burning gasoline for nearly one-third of the travel covered in EV mode.

Regulatory and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output enabled four large carmaker groups to escape more than €5bn in penalties from 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would spend approximately €500 more per year in operating expenses than would be estimated under lab conditions.

“The bold statements that automakers like to make about their PHEV vehicles are clearly way off the truth,” stated a automotive expert. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are little better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and running costs.”

Policy Discussion and Industry Lobbying

Hybrid vehicles have lately been drawn again into political debates as carmakers have lobbied the European Union to relax CO₂ standards. A proposed ban on new internal combustion vehicles in 2035 has faced intense pressure from the car sector and resistance from member states with significant automotive industries.

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

One independent energy economics expert, who was unaffiliated with the study, called the analysis a “very useful contribution” after a long period in which segments of the automotive industry claimed there was insufficient data to properly evaluate actual emissions.

“These findings show, without question, that the difference between lab and real-world PHEV energy use and CO₂ output is significantly larger than for petrol or conventional vehicles,” they stated. “Any regulatory adjustments concerning PHEVs should be implemented with extreme care and considering that evidence.”