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Plug-in hybrid electric vehicles emit almost 5x greater planet-heating emissions than lab-reported data indicate, according to a new analysis.

Growing Gap Between Official and Actual CO2 Output

Data reveals that PHEVs emit only one-fifth less CO₂ than traditional petrol and diesel cars, based on analysis conducted by a non-profit organization. That contrasts sharply with lab estimates, which suggested a 75% decrease in pollution.

Researchers studied information from in-vehicle fuel consumption meters of eight hundred thousand vehicles sold in the EU between 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official figures are falling,” stated a senior researcher participating in the study. “That discrepancy is widening and poses a significant issue. As a result, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Factors Driving the Emissions Gap

Researchers linked most of the difference to overestimates of the “utility factor” – the percentage of kilometers driven in battery power compared to total mileage. The team found that only a quarter of travel was completed in electric mode, whereas lab assumptions suggested over four-fifths.

Even, when operating in electric mode, pollution amounts were well above lab projections. This occurred because electric motors were not strong sufficient to function independently, leading to engines burning gasoline for nearly a third of the distance completed in EV mode.

Regulatory and Economic Implications

According to estimates, the lowballing of PHEV emissions enabled several large carmaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs could spend approximately €500 more annually in operating expenses than would be estimated under lab tests.

“The bold claims that automakers like to make about their PHEV cars are clearly way off the truth,” commented a automotive analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are only slightly better than standard gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running costs.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have lately been brought back into policy debates as carmakers have lobbied the EU to relax 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 EU countries with large car manufacturing.

Some high-level politicians have suggested PHEVs as a potential “flexibility” solution to include in the regulation.

One external energy policy specialist, who was not involved with the study, called the analysis a “very useful contribution” after years in which segments of the automotive industry claimed there was too little information to properly evaluate real-world CO2 output.

“The results show, beyond any doubt, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or conventional vehicles,” they said. “All regulatory changes concerning PHEVs should be implemented with utmost caution and in the light of this data.”