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PHEVs release almost five times greater planet-heating emissions than official data indicate, as per a recent report.

Widening Gap In Official and Actual CO2 Output

Data shows that PHEVs emit just one-fifth less CO₂ than traditional petrol and diesel vehicles, based on research carried out by a non-profit organization. This contrasts significantly with lab estimates, which assumed a 75% reduction in pollution.

Researchers examined data from in-vehicle fuel consumption monitors of 800,000 cars sold in the EU between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from 3.5 times in 2021.

“Real-world emissions are rising, while official figures are falling,” said a lead analyst involved in the report. “This discrepancy is growing and poses a significant problem. As a result, PHEVs emit almost as much as petrol vehicles.”

Primary Factors Behind the Emissions Gap

Analysts linked most of the gap to overestimates of the “electric driving share” – the percentage of miles travelled in battery mode relative to total distance. They determined that just a quarter of travel was done in electric mode, whereas official estimates assumed over four-fifths.

Even, when operating in electric mode, pollution amounts were significantly higher than official estimates. This happened because EV motors were insufficiently powerful enough to function independently, leading to engines using gasoline for nearly a third of the distance completed in electric mode.

Policy and Economic Implications

According to calculations, the underestimation of PHEV CO2 output enabled four major carmaker groups to avoid over €5bn in penalties from 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs could pay about €500 extra annually in operating costs than would be estimated under lab tests.

“The strong claims that automakers like to make about their plug-in hybrid cars are clearly way off the mark,” stated a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Policy Debate and Industry Pressure

Plug-in hybrid vehicles have lately been brought back into policy debates as carmakers have lobbied the EU to relax CO₂ standards. A planned prohibition on new internal combustion vehicles in 2035 has faced intense pressure from the car industry and opposition from member states with large car manufacturing.

Several high-level politicians have suggested PHEVs as a possible “compromise” option to introduce in the regulation.

An independent energy economics expert, who was not involved with the study, called the report a “very useful addition” after years in which segments of the automotive industry argued there was insufficient data to properly assess real-world emissions.

“These findings show, without question, that the difference in lab and actual PHEV energy use and CO₂ emissions is significantly larger than for gasoline or diesel cars,” they stated. “Any policy changes concerning PHEVs should be implemented with extreme caution and in the light of that evidence.”