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Plug-in hybrid cars release almost 5x greater planet-heating emissions than lab-reported figures indicate, according to a new report.

Growing Discrepancy In Lab and Actual CO2 Output

Statistics shows that PHEVs emit just 19% less CO₂ than conventional gas and diesel vehicles, according to analysis carried out by a advocacy group. This differs sharply with laboratory tests, which suggested a 75% reduction in pollution.

Analysts examined data from in-vehicle energy use monitors of 800,000 vehicles registered in Europe between 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, increased from 3.5 times in 2021.

“Real-world emissions are rising, while official figures are falling,” said a senior analyst involved in the report. “This gap is growing and creates a serious issue. As a result, PHEVs pollute nearly as heavily as petrol cars.”

Primary Reasons Behind the Emissions Gap

Analysts linked most of the difference to inflated estimates of the “utility factor” – the ratio of kilometers driven in electric mode compared to overall mileage. The team determined that only 27% of travel was done in EV mode, whereas official estimates suggested 84%.

Additionally, when running in EV mode, emission amounts were significantly higher than official projections. This happened because electric motors were not strong enough to function independently, leading to combustion motors using gasoline for almost one-third of the distance completed in EV mode.

Regulatory and Financial Consequences

Based on estimates, the lowballing of PHEV CO2 output enabled several major carmaker companies to escape over €5bn in fines between 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs would spend about €500 extra per year in operating expenses than is assumed under lab tests.

“The strong claims that automakers like to make about their PHEV cars are clearly way off the truth,” stated a transport analyst. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are only slightly improved than regular petrol and diesel cars in terms of energy use, CO₂ emissions, and operating expenses.”

Political Discussion and Automotive Pressure

Hybrid cars have recently been brought back into policy discussions as carmakers have pressed the EU to weaken CO₂ standards. A planned prohibition on sales of new internal combustion cars in 2035 has faced heavy lobbying from the car sector and resistance from member states with significant automotive manufacturing.

Several high-level officials have proposed PHEVs as a potential “flexibility” option to introduce in the regulation.

An external energy policy expert, who was unaffiliated with the research, called the report a “very useful contribution” after years in which parts of the car sector argued there was insufficient data to properly assess actual emissions.

“The results demonstrate, beyond any doubt, that the difference between lab and actual PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or diesel cars,” they said. “Any regulatory adjustments concerning PHEVs should be implemented with extreme caution and in the light of that evidence.”