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Plug-in hybrid electric vehicles produce almost five times greater planet-heating pollution than official data show, according to a new analysis.

Widening Gap In Lab and Real-World Emissions

Statistics shows that PHEVs emit just 19% lower CO₂ than traditional gas and diesel vehicles, based on research carried out by a advocacy organization. That differs sharply with laboratory tests, which suggested a 75% reduction in emissions.

Researchers studied information from onboard energy use meters of eight hundred thousand vehicles sold in the EU between 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than official figures, increased from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported figures are decreasing,” stated a senior researcher participating in the report. “This discrepancy is growing and creates a significant issue. As a result, PHEVs emit almost as much as gasoline cars.”

Primary Factors Behind the Emissions Gap

Analysts linked most of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in battery power relative to overall distance. They found that just a quarter of travel was done in EV mode, whereas official assumptions suggested 84%.

Additionally, when operating in EV mode, pollution levels were significantly higher than lab estimates. That occurred because electric motors were insufficiently powerful enough to operate alone, resulting to engines burning fossil fuels for almost one-third of the travel covered in EV mode.

Regulatory and Financial Consequences

According to estimates, the lowballing of PHEV CO2 output allowed several major automaker companies to escape over €5bn in fines from 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ standards.

Additionally, owners of PHEVs could pay approximately €500 more per year in operating expenses than is estimated under lab tests.

“The strong claims that manufacturers like to make about their plug-in hybrid cars are clearly way off the mark,” commented a automotive analyst. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are only slightly improved than regular gas and diesel cars in terms of energy use, CO₂ production, and running expenses.”

Political Debate and Industry Pressure

Hybrid cars have recently been brought back into policy debates as carmakers have pressed the European Union to weaken CO₂ standards. A proposed prohibition on sales of new internal combustion cars in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with large car manufacturing.

Some senior officials have proposed plug-in hybrids as a potential “flexibility” option to introduce in the legislation.

One external energy policy specialist, 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 too little data to properly evaluate real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the gap in lab and real-world PHEV fuel consumption and CO₂ output is much, much larger than for petrol or diesel vehicles,” they stated. “Any policy changes regarding PHEVs should be implemented with utmost care and considering that evidence.”