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PHEVs release almost five times more global warming emissions than lab-reported figures show, according to a new report.

Widening Discrepancy Between Official and Actual CO2 Output

Data reveals that PHEVs release only 19% less CO₂ than conventional gas and diesel vehicles, according to research conducted by a advocacy group. That contrasts sharply with laboratory tests, which suggested a 75% reduction in pollution.

Researchers studied data from onboard energy use monitors of 800,000 cars sold in Europe between 2021 and 2023. The team found 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.

“Real-world emissions are rising, while official figures are falling,” said a lead analyst participating in the report. “That gap is widening and creates a serious issue. As a result, PHEVs emit almost as much as petrol cars.”

Key Reasons Behind the Discrepancy

Analysts attributed most of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in battery mode compared to overall mileage. The team determined that only a quarter of travel was done in EV mode, while official assumptions suggested 84%.

Additionally, when running in electric mode, emission amounts were well above lab projections. That happened because electric motors were not strong enough to function alone, resulting to combustion motors using fossil fuels for almost a third of the distance covered in EV mode.

Policy and Economic Implications

Based on calculations, the lowballing of PHEV emissions enabled four large carmaker companies to escape over €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with EU average fleet CO₂ standards.

Additionally, drivers of PHEVs could pay approximately €500 more annually in running expenses than is assumed under laboratory tests.

“The strong statements that automakers like to make about their plug-in hybrid cars are clearly way off the truth,” stated a automotive analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are little improved than regular petrol and diesel vehicles in terms of fuel use, CO₂ production, and running costs.”

Political Debate and Industry Lobbying

Plug-in hybrid cars have recently been brought back into political discussions as automakers have lobbied the EU to relax CO₂ targets. A planned ban on sales of new combustion engine vehicles in 2035 has faced intense pressure from the car industry and opposition from member states with significant car industries.

Several senior officials have proposed PHEVs as a potential “compromise” option to introduce in the legislation.

One independent energy economics expert, who was not involved with the study, called the report a “highly valuable contribution” after years in which segments of the car industry claimed there was insufficient information to properly evaluate actual emissions.

“The results demonstrate, without question, that the difference in lab and actual PHEV fuel consumption and CO₂ output is significantly greater than for petrol or diesel vehicles,” the expert stated. “Any policy adjustments concerning PHEVs should be made with utmost care and considering that data.”