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Plug-in hybrid electric vehicles emit almost 5x more global warming pollution than lab-reported figures indicate, as per a recent report.

Widening Discrepancy In Official and Actual Emissions

Statistics shows that PHEVs release only 19% lower CO₂ than traditional gas and diesel cars, based on research carried out by a non-profit organization. This differs sharply with lab tests, which assumed a 75% reduction in emissions.

Analysts examined information from in-vehicle energy use meters of 800,000 vehicles registered in the EU from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, up from three and a half times in 2021.

“Actual emissions are rising, while lab-reported figures are decreasing,” said a senior analyst participating in the report. “That discrepancy is growing and poses a serious problem. Consequently, PHEVs emit almost as heavily as petrol cars.”

Key Reasons Behind the Discrepancy

Analysts linked the majority of the difference to overestimates of the “utility factor” – the percentage of kilometers travelled in battery mode relative to total mileage. They found that just 27% of driving was done in electric mode, while lab assumptions suggested over four-fifths.

Even, when running in EV mode, emission amounts were well above lab estimates. This occurred because electric motors were insufficiently powerful enough to function alone, resulting to combustion motors using fossil fuels for nearly one-third of the distance completed in electric mode.

Regulatory and Economic Implications

Based on estimates, the underestimation of PHEV emissions enabled four large automaker companies to avoid more than €5bn in fines between 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs could spend about €500 extra annually in running expenses than is assumed under lab conditions.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are clearly way off the truth,” commented a transport expert. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are little better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and running expenses.”

Political Debate and Industry Pressure

Plug-in hybrid vehicles have recently been brought again into political debates as carmakers have pressed the EU to relax CO₂ targets. A planned ban on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and resistance from EU countries with large automotive manufacturing.

Some senior officials have suggested PHEVs as a potential “flexibility” option to include in the legislation.

An independent energy economics expert, who was not involved with the research, described the report a “very useful addition” after years in which segments of the automotive sector claimed there was insufficient data to accurately evaluate actual emissions.

“These findings demonstrate, without question, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or conventional cars,” the expert stated. “Any policy adjustments concerning PHEVs should be implemented with utmost caution and in the light of this evidence.”