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PHEVs release almost five times more planet-heating pollution than lab-reported figures indicate, according to a recent analysis.

Widening Discrepancy In Lab and Real-World CO2 Output

Statistics shows that PHEVs release only 19% lower CO₂ than conventional petrol and diesel cars, according to research carried out by a advocacy organization. That contrasts significantly with lab tests, which suggested a three-quarters decrease in pollution.

Analysts examined data from onboard energy use monitors of eight hundred thousand vehicles sold in Europe between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported figures are falling,” said a lead analyst involved in the report. “That gap is growing and creates a serious issue. Consequently, PHEVs emit nearly as much as gasoline vehicles.”

Primary Reasons Behind the Discrepancy

Researchers linked most of the difference to inflated estimates of the “utility factor” – the percentage of miles travelled in battery mode relative to overall mileage. They determined that just 27% of travel was completed in electric mode, while lab estimates assumed 84%.

Even, when running in EV mode, pollution amounts were significantly higher than lab estimates. That occurred because EV motors were not strong sufficient to function independently, resulting to engines burning gasoline for almost one-third of the travel covered in EV mode.

Regulatory and Financial Consequences

Based on estimates, the lowballing of PHEV emissions enabled several large automaker groups to escape more than €5bn in penalties from 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs would pay about €500 more per year in running expenses than is estimated under lab tests.

“The bold claims that automakers like to make about their PHEV cars are obviously way off the truth,” commented a transport analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and cutting money. Actually, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and operating costs.”

Policy Debate and Industry Pressure

Hybrid vehicles have lately been drawn back into policy discussions as carmakers have pressed the European Union to weaken CO₂ standards. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the car sector and opposition from EU countries with significant car manufacturing.

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

An external energy policy specialist, who was not involved with the research, called the report a “highly valuable addition” after years in which segments of the automotive sector argued there was too little information to accurately assess real-world CO2 output.

“These findings demonstrate, without question, that the difference between lab and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or diesel cars,” the expert stated. “All policy changes regarding PHEVs should be implemented with utmost care and in the light of this evidence.”