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Plug-in hybrid cars release almost 5x greater planet-heating emissions than official data show, as per a recent report.

Widening Discrepancy In Lab and Real-World Emissions

Data shows that PHEVs release just 19% lower CO₂ than conventional gas and diesel cars, based on analysis conducted by a non-profit group. This differs sharply with laboratory estimates, which suggested a 75% decrease in pollution.

Researchers studied information from onboard fuel consumption monitors of 800,000 vehicles registered in Europe from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are falling,” stated a senior analyst involved in the report. “This discrepancy is growing and poses a significant issue. Consequently, PHEVs emit nearly as much as petrol cars.”

Primary Factors Behind the Discrepancy

Researchers linked the majority of the difference to overestimates of the “utility factor” – the ratio of miles driven in battery mode relative to total mileage. They found that only a quarter of travel was done in EV mode, whereas lab assumptions suggested over four-fifths.

Additionally, when operating in EV mode, pollution amounts were well above lab projections. This happened because electric motors were not strong enough to operate alone, leading to combustion motors using gasoline for nearly one-third of the travel completed in electric mode.

Policy and Financial Consequences

Based on estimates, the underestimation of PHEV emissions allowed several large carmaker companies to avoid more than €5bn in fines from 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ targets.

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

“The bold claims that automakers like to make about their plug-in hybrid cars are clearly far from the mark,” commented a transport analyst. “Buyers are being duped into believing that by buying a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are little improved than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and operating costs.”

Policy Debate and Industry Lobbying

Hybrid cars have lately been drawn back into political debates as automakers have lobbied the EU to relax CO₂ targets. A planned prohibition on new combustion engine vehicles in 2035 has faced intense lobbying from the automotive sector and opposition from member states with significant car industries.

Some high-level officials have proposed plug-in hybrids as a potential “compromise” solution to introduce in the regulation.

An independent energy policy specialist, who was not involved with the research, called the analysis a “highly valuable contribution” after a long period in which segments of the automotive industry argued there was insufficient data to properly assess actual CO2 output.

“The results demonstrate, beyond any doubt, that the difference in official and real-world PHEV energy use and CO₂ output is significantly larger than for gasoline or conventional cars,” they stated. “All policy adjustments regarding PHEVs should be made with utmost care and in the light of that data.”