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PHEVs emit nearly five times more global warming pollution than official figures show, as per a recent report.

Widening Gap In Lab and Real-World CO2 Output

Data reveals that PHEVs emit only 19% less CO₂ than conventional gas and diesel cars, according to research carried out by a non-profit organization. That contrasts sharply with laboratory tests, which assumed a three-quarters reduction in pollution.

Analysts examined information from in-vehicle energy use monitors of 800,000 cars sold in the EU from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, increased from 3.5 times in 2021.

“Real-world CO2 output are rising, while official emissions are falling,” stated a lead analyst involved in the study. “That discrepancy is widening and poses a serious issue. Consequently, PHEVs emit almost as much as petrol cars.”

Key Reasons Behind the Emissions Gap

Researchers linked most of the gap to overestimates of the “electric driving share” – the percentage of kilometers travelled in battery power compared to overall mileage. The team determined that only 27% of driving was completed in EV mode, while official assumptions assumed over four-fifths.

Additionally, when running in electric mode, pollution levels were significantly higher than lab projections. That occurred because electric motors were not strong enough to operate alone, leading to combustion motors using fossil fuels for almost one-third of the distance covered in electric mode.

Policy and Economic Implications

Based on estimates, the underestimation of PHEV emissions enabled several major carmaker groups to avoid over €5bn in fines between 2021 and 2023, by falsely simplifying adherence with EU average fleet CO₂ targets.

Additionally, owners of PHEVs could spend approximately €500 more per year in operating costs than is assumed under laboratory tests.

“The strong statements that manufacturers like to make about their PHEV vehicles are clearly far from the truth,” commented a transport expert. “Buyers are being duped into thinking that by buying a PHEV, they are helping the planet and saving money. Actually, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel consumption, CO₂ production, and operating costs.”

Political Discussion and Automotive Pressure

Plug-in hybrid vehicles have lately been drawn again into policy discussions as automakers have pressed the EU to weaken CO₂ targets. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and opposition from EU countries with large automotive manufacturing.

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

An external energy policy specialist, who was not involved with the study, called the report a “very useful contribution” after a long period in which segments of the car industry claimed there was insufficient information to accurately evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the gap between lab and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional cars,” they said. “All regulatory changes regarding PHEVs should be made with utmost care and considering this data.”