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PHEVs emit nearly five times greater planet-heating pollution than lab-reported figures indicate, according to a recent report.

Widening Gap Between Lab and Real-World CO2 Output

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

Analysts studied data from onboard energy use meters of 800,000 cars sold in Europe from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are decreasing,” stated a lead researcher participating in the report. “That gap is growing and creates a serious problem. As a result, PHEVs emit nearly as heavily as gasoline cars.”

Primary Reasons Driving the Emissions Gap

Analysts linked most of the difference to overestimates of the “electric driving share” – the ratio of miles travelled in electric mode compared to overall distance. The team found that only a quarter of driving was done in EV mode, while official assumptions suggested 84%.

Additionally, when running in electric mode, pollution levels were well above official projections. That happened because electric motors were insufficiently powerful sufficient to operate independently, leading to engines using fossil fuels for almost a third of the travel completed in electric mode.

Policy and Financial Implications

Based on calculations, the lowballing of PHEV CO2 output allowed several major automaker companies to avoid more than €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs could pay about €500 extra per year in running expenses than would be estimated under laboratory conditions.

“The strong statements that automakers like to make about their plug-in hybrid vehicles are clearly far from the truth,” commented a automotive expert. “Buyers are being duped into believing that by buying a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly better than regular gas and diesel cars in terms of fuel use, CO₂ emissions, and operating expenses.”

Policy Debate and Automotive Lobbying

Plug-in hybrid cars have lately been drawn back into political discussions as automakers have lobbied the European Union to weaken CO₂ targets. A planned ban on sales of new combustion engine cars in 2035 has faced heavy lobbying from the car industry and resistance from EU countries with large automotive manufacturing.

Several senior politicians have proposed plug-in hybrids as a potential “compromise” option to include in the legislation.

One external energy economics specialist, who was not involved with the study, called the report a “very useful contribution” after a long period in which parts of the car sector argued there was insufficient data to properly evaluate actual CO2 output.

“These findings show, without question, that the difference in lab and real-world PHEV energy use and CO₂ emissions is significantly larger than for gasoline or diesel cars,” the expert said. “Any regulatory adjustments regarding PHEVs should be implemented with utmost care and considering this data.”