🔗 Share this article

PHEVs produce almost five times greater global warming emissions than lab-reported figures show, as per a new analysis.

Growing Gap Between Official and Actual Emissions

Data shows that PHEVs release just 19% less CO₂ than conventional petrol and diesel vehicles, according to research carried out by a advocacy organization. That contrasts sharply with laboratory tests, which assumed a three-quarters reduction in pollution.

Researchers studied data from in-vehicle energy use meters of 800,000 vehicles registered in the EU from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while official emissions are falling,” stated a senior analyst involved in the study. “That gap is widening and poses a serious issue. As a result, PHEVs emit almost as heavily as gasoline cars.”

Primary Factors Driving the Discrepancy

Researchers linked most of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in battery mode compared to total distance. They found that only 27% of driving was completed in electric mode, whereas official estimates suggested over four-fifths.

Even, when running in electric mode, pollution amounts were significantly higher than lab estimates. This occurred because EV motors were insufficiently powerful enough to function alone, leading to combustion motors using fossil fuels for almost a third of the distance completed in EV mode.

Regulatory and Financial Consequences

According to calculations, the underestimation of PHEV emissions enabled several major automaker companies to avoid over €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ targets.

Additionally, owners of PHEVs would pay about €500 more per year in running expenses than would be assumed under laboratory conditions.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are obviously way off the truth,” commented a automotive analyst. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are little improved than regular gas and diesel vehicles in terms of fuel consumption, CO₂ production, and operating costs.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have lately been drawn back into political debates as automakers have pressed the EU to weaken CO₂ standards. A planned prohibition on new combustion engine cars in 2035 has faced intense pressure from the automotive sector and opposition from member states with significant car industries.

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

An external energy economics specialist, who was not involved with the study, called the report a “very useful contribution” after years in which segments of the car sector argued there was too little data to accurately assess real-world emissions.

“These findings show, beyond any doubt, that the difference in official and actual PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or conventional vehicles,” they said. “Any policy adjustments concerning PHEVs should be made with extreme caution and in the light of that evidence.”