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Plug-in hybrid cars emit almost five times more global warming emissions than official data show, according to a new report.

Growing Gap In Lab and Actual Emissions

Data reveals that PHEVs emit just one-fifth lower CO₂ than conventional gas and diesel cars, based on analysis carried out by a non-profit group. That contrasts significantly with laboratory estimates, which assumed a 75% reduction in emissions.

Analysts examined information from in-vehicle energy use monitors of eight hundred thousand vehicles registered in Europe between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are decreasing,” said a senior analyst involved in the report. “That discrepancy is widening and creates a significant problem. As a result, PHEVs pollute almost as much as gasoline vehicles.”

Primary Factors Behind the Discrepancy

Researchers linked the majority of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers driven in electric power relative to overall distance. The team determined that just 27% of driving was done in EV mode, whereas official estimates assumed over four-fifths.

Additionally, when operating in EV mode, pollution amounts were well above lab projections. That happened because electric motors were not strong sufficient to function independently, resulting to engines using fossil fuels for nearly one-third of the travel completed in electric mode.

Regulatory and Economic Implications

Based on estimates, the lowballing of PHEV CO2 output allowed four major carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs would spend about €500 more per year in running expenses than is assumed under laboratory tests.

“The bold statements that automakers like to make about their plug-in hybrid cars are obviously way off the mark,” stated a automotive expert. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are little improved than regular gas and diesel cars in terms of energy consumption, CO₂ emissions, and operating costs.”

Policy Discussion and Industry Lobbying

Hybrid cars have recently been drawn back into political discussions as carmakers have pressed the EU to relax CO₂ standards. A proposed prohibition on new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and opposition from member states with significant car manufacturing.

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

One independent energy policy expert, who was not involved with the study, described the analysis a “highly valuable addition” after a long period in which parts of the car industry claimed there was too little data to properly evaluate actual CO2 output.

“The results demonstrate, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or diesel vehicles,” the expert stated. “All policy changes concerning PHEVs should be made with utmost caution and in the light of that data.”