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Plug-in hybrid cars emit almost five times more global warming pollution than official data show, as per a recent analysis.

Growing Gap In Lab and Real-World Emissions

Data shows that PHEVs emit only one-fifth lower CO₂ than conventional gas and diesel cars, based on research conducted by a advocacy group. This contrasts significantly with lab estimates, which assumed a three-quarters reduction in emissions.

Researchers studied data from onboard energy use meters of 800,000 vehicles registered in Europe between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, increased from three and a half times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are falling,” stated a senior researcher participating in the study. “This discrepancy is growing and poses a significant problem. Consequently, PHEVs pollute almost as heavily as gasoline vehicles.”

Key Reasons Behind the Emissions Gap

Researchers attributed the majority of the gap to overestimates of the “utility factor” – the ratio of kilometers driven in battery mode relative to total distance. They determined that just a quarter of driving was completed in EV mode, while lab assumptions assumed over four-fifths.

Additionally, when running in electric mode, pollution levels were significantly higher than official estimates. This occurred because electric motors were not strong enough to operate independently, resulting to combustion motors burning gasoline for almost one-third of the distance completed in electric mode.

Policy and Financial Implications

Based on calculations, the lowballing of PHEV emissions enabled four large carmaker companies to avoid more than €5bn in fines from 2021 and 2023, by artificially simplifying compliance with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs would spend about €500 more annually in operating costs than is assumed under laboratory tests.

“The bold statements that automakers often promote about their plug-in hybrid vehicles are clearly far from the truth,” stated a transport analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of fuel use, CO₂ production, and running expenses.”

Political Debate and Automotive Lobbying

Hybrid cars have lately been drawn back into political discussions as automakers have pressed the European Union to weaken CO₂ standards. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the car industry and resistance from member states with significant car manufacturing.

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

An external energy policy expert, who was unaffiliated with the research, called the report a “highly valuable addition” after a long period in which parts of the automotive sector argued there was insufficient information to accurately evaluate actual CO2 output.

“These findings show, without question, that the gap between official and actual PHEV energy use and CO₂ emissions is significantly larger than for petrol or conventional cars,” the expert stated. “Any policy changes concerning PHEVs should be made with extreme caution and in the light of this data.”