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Plug-in hybrid cars emit nearly 5x greater global warming pollution than official figures show, as per a recent analysis.

Growing Discrepancy In Lab and Real-World CO2 Output

Statistics reveals that PHEVs release just one-fifth lower CO₂ than conventional gas and diesel cars, according to research conducted by a advocacy group. That differs significantly with laboratory estimates, which suggested a 75% reduction in emissions.

Analysts 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 emissions from PHEVs in 2023 were 4.9 times higher than lab figures, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are falling,” said a lead researcher involved in the study. “That discrepancy is widening and poses a serious issue. Consequently, PHEVs emit nearly as much as gasoline cars.”

Key Reasons Behind the Discrepancy

Analysts attributed the majority of the difference to overestimates of the “utility factor” – the percentage of miles travelled in electric mode relative to total distance. The team determined that just a quarter of travel was done in EV mode, while lab assumptions suggested 84%.

Additionally, when operating in electric mode, emission amounts were significantly higher than official estimates. That occurred because electric motors were insufficiently powerful sufficient to operate independently, leading to combustion motors burning fossil fuels for almost a third of the travel covered in electric mode.

Regulatory and Financial Consequences

Based on estimates, the underestimation of PHEV CO2 output allowed four major carmaker groups to escape more than €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ targets.

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

“The strong claims that manufacturers often promote about their plug-in hybrid cars are clearly far from the truth,” stated a transport expert. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the planet and saving money. Actually, PHEVs are only slightly better than standard gas and diesel cars in terms of energy consumption, CO₂ production, and running costs.”

Policy Debate and Industry Lobbying

Plug-in hybrid cars have recently been drawn back into political debates as automakers have lobbied the European Union to relax CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the automotive sector and resistance from member states with large automotive manufacturing.

Some senior politicians have proposed plug-in hybrids as a possible “compromise” solution to introduce in the regulation.

One external energy policy specialist, who was unaffiliated with the research, described the analysis a “very useful contribution” after a long period in which segments of the automotive sector argued there was too little information to accurately assess actual emissions.

“These findings show, without question, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional cars,” they said. “Any regulatory changes regarding PHEVs should be made with utmost care and in the light of that evidence.”