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Plug-in hybrid cars release nearly 5x more planet-heating emissions than lab-reported figures indicate, according to a recent analysis.

Widening Discrepancy Between Official and Actual CO2 Output

Data shows that PHEVs release only one-fifth lower CO₂ than traditional petrol and diesel vehicles, according to analysis carried out by a non-profit organization. This differs sharply with lab estimates, which suggested a 75% reduction in emissions.

Analysts examined data from in-vehicle fuel consumption monitors of 800,000 vehicles sold in the EU between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, up from three and a half times in 2021.

“Actual CO2 output are rising, while official emissions are decreasing,” said a lead analyst participating in the study. “That gap is widening and creates a significant problem. Consequently, PHEVs emit almost as much as gasoline cars.”

Primary Factors Behind the Emissions Gap

Analysts linked the majority of the gap to inflated estimates of the “utility factor” – the ratio of kilometers travelled in electric mode compared to overall mileage. The team found that only 27% of driving was completed in electric mode, whereas official assumptions suggested over four-fifths.

Even, when running in electric mode, pollution amounts were significantly higher than lab projections. That happened because electric motors were insufficiently powerful sufficient to function alone, resulting to engines burning fossil fuels for almost a third of the travel completed in electric mode.

Regulatory and Financial Consequences

According to calculations, the lowballing of PHEV emissions allowed several major automaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs could spend about €500 more per year in operating expenses than would be assumed under lab tests.

“The bold statements that manufacturers like to make about their PHEV vehicles are obviously far from the mark,” stated a automotive expert. “Buyers are being duped into thinking that by buying a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of fuel use, CO₂ production, and running expenses.”

Political Debate and Industry Lobbying

Hybrid vehicles have recently been drawn back into policy debates as carmakers have pressed the EU to relax CO₂ standards. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the car sector and resistance from member states with large automotive industries.

Some high-level politicians have proposed plug-in hybrids as a potential “flexibility” option to introduce in the legislation.

An independent energy policy expert, who was not involved with the study, described the report a “very useful contribution” after years in which segments of the car industry claimed there was insufficient information to properly assess real-world CO2 output.

“These findings show, beyond any doubt, that the difference in lab and actual PHEV energy use and CO₂ emissions is much, much greater than for gasoline or diesel cars,” they stated. “Any policy changes regarding PHEVs should be implemented with utmost care and in the light of this evidence.”