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Plug-in hybrid cars emit nearly 5x more global warming emissions than lab-reported figures show, as per a recent analysis.

Growing Discrepancy In Official and Real-World CO2 Output

Data reveals that PHEVs release only 19% lower CO₂ than conventional petrol and diesel vehicles, based on analysis carried out by a non-profit organization. This differs sharply with lab tests, which suggested a 75% reduction in pollution.

Researchers studied data from in-vehicle energy use monitors of 800,000 cars registered in the EU between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, up from three and a half times in 2021.

“Actual emissions are rising, while official figures are falling,” said a lead analyst participating in the study. “This gap is widening and poses a serious problem. As a result, PHEVs pollute almost as heavily as petrol vehicles.”

Primary Reasons Driving the Discrepancy

Analysts attributed the majority of the gap to overestimates of the “utility factor” – the percentage of kilometers driven in electric mode compared to overall mileage. The team found that just a quarter of driving was completed in EV mode, while lab assumptions suggested 84%.

Even, when running in EV mode, pollution levels were well above lab projections. That happened because electric motors were not strong enough to function independently, leading to combustion motors using fossil fuels for nearly one-third of the travel covered in electric mode.

Regulatory and Financial Consequences

According to estimates, the lowballing of PHEV CO2 output allowed several major carmaker groups to avoid over €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs would pay approximately €500 extra per year in operating costs than would be estimated under laboratory conditions.

“The strong claims that automakers often promote about their PHEV vehicles are clearly way off the mark,” stated a automotive 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 better than regular petrol and diesel cars in terms of energy consumption, CO₂ production, and running costs.”

Policy Debate and Industry Pressure

Hybrid cars have recently been drawn back into political discussions as automakers have pressed the European Union to weaken CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced heavy pressure from the car sector and opposition from EU countries with large car industries.

Some senior politicians have proposed plug-in hybrids as a potential “compromise” solution to introduce in the legislation.

One independent energy economics expert, who was not involved with the research, described the analysis a “very useful addition” after a long period in which segments of the automotive sector claimed there was insufficient information to accurately evaluate real-world emissions.

“These findings show, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ output is much, much greater than for petrol or diesel cars,” they stated. “Any policy adjustments concerning PHEVs should be implemented with utmost care and considering this data.”