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

Growing Discrepancy In Lab and Actual Emissions

Statistics reveals that PHEVs release only 19% less CO₂ than traditional gas and diesel cars, according to analysis conducted by a non-profit group. This contrasts sharply with laboratory tests, which assumed a three-quarters decrease in pollution.

Researchers studied information from in-vehicle fuel consumption monitors of eight hundred thousand cars registered in Europe from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official figures, increased from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported figures are falling,” said a senior researcher involved in the report. “That discrepancy is widening and creates a significant problem. Consequently, PHEVs pollute almost as heavily as petrol vehicles.”

Key Factors Driving the Emissions Gap

Researchers linked the majority of the difference to inflated estimates of the “utility factor” – the percentage of kilometers travelled in electric mode relative to total mileage. They determined that only 27% of travel was completed in EV mode, whereas official estimates suggested 84%.

Additionally, when operating in EV mode, pollution levels were well above official projections. This occurred because EV motors were insufficiently powerful enough to operate independently, resulting to engines burning gasoline for almost one-third of the travel covered in EV mode.

Policy and Financial Consequences

According to calculations, the lowballing of PHEV CO2 output allowed several major carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 more annually in operating expenses than is estimated under lab conditions.

“The strong claims that manufacturers like to make about their plug-in hybrid vehicles are clearly way off the mark,” commented a automotive analyst. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are only slightly better than regular gas and diesel cars in terms of energy consumption, CO₂ production, and operating expenses.”

Political Discussion and Industry Lobbying

Plug-in hybrid cars have recently been brought again into political debates as automakers have lobbied the European Union to relax CO₂ standards. A planned ban on sales of new combustion engine cars in 2035 has faced heavy pressure from the automotive industry and resistance from member states with large car industries.

Some high-level politicians have proposed PHEVs as a possible “flexibility” solution to introduce in the legislation.

An independent energy policy specialist, who was not involved with the study, described the report a “highly valuable contribution” after years in which segments of the car industry argued there was too little information to properly assess actual emissions.

“The results show, without question, that the difference between official and actual PHEV fuel consumption and CO₂ output is much, much larger than for gasoline or conventional vehicles,” the expert stated. “All regulatory adjustments regarding PHEVs should be implemented with utmost caution and in the light of that evidence.”