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PHEVs emit almost five times greater planet-heating pollution than official data indicate, according to a new analysis.

Widening Gap In Official and Actual Emissions

Data reveals that PHEVs release only 19% less CO₂ than traditional gas and diesel vehicles, according to research conducted by a non-profit organization. This contrasts sharply with lab tests, which assumed a 75% decrease in pollution.

Researchers studied information from onboard energy use monitors of 800,000 vehicles registered in the EU from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official estimates, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while official figures are decreasing,” stated a lead analyst involved in the study. “That discrepancy is widening and creates a significant issue. As a result, PHEVs pollute nearly as heavily as petrol cars.”

Key Factors Driving the Discrepancy

Analysts linked most of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric mode relative to overall mileage. They determined that only a quarter of travel was done in electric mode, while lab assumptions assumed 84%.

Additionally, when running in EV mode, pollution amounts were well above lab projections. That occurred because EV motors were insufficiently powerful sufficient to function alone, resulting to combustion motors burning gasoline for almost one-third of the distance completed in electric mode.

Policy and Financial Implications

According to estimates, the lowballing of PHEV CO2 output enabled four large automaker companies to escape over €5bn in fines from 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs could pay about €500 extra per year in running costs than would be estimated under laboratory conditions.

“The strong claims that manufacturers like to make about their plug-in hybrid cars are obviously way off the mark,” commented a transport analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are little better than standard gas and diesel vehicles in terms of fuel consumption, CO₂ production, and running costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid vehicles have lately been drawn back into policy discussions as carmakers have pressed the EU to relax CO₂ standards. A planned ban on new combustion engine vehicles in 2035 has faced heavy pressure from the automotive industry and resistance from EU countries with large automotive manufacturing.

Some senior politicians have proposed PHEVs as a potential “compromise” solution to introduce in the regulation.

One independent energy economics specialist, who was unaffiliated with the study, described the report a “highly valuable contribution” after years in which parts of the automotive industry claimed there was insufficient information to properly assess real-world CO2 output.

“The results demonstrate, without question, that the difference in lab and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional cars,” they stated. “All regulatory changes concerning PHEVs should be implemented with utmost care and in the light of this data.”