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PHEVs produce nearly five times more planet-heating emissions than official figures show, according to a recent analysis.

Growing Discrepancy Between Lab and Actual Emissions

Data shows that PHEVs emit only one-fifth lower CO₂ than conventional gas and diesel cars, based on analysis carried out by a advocacy organization. That differs sharply with laboratory estimates, which assumed a three-quarters decrease in emissions.

Analysts studied data from in-vehicle fuel consumption monitors of 800,000 cars registered in the EU between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official emissions are falling,” said a senior researcher participating in the study. “That gap is growing and poses a significant issue. As a result, PHEVs pollute nearly as heavily as gasoline vehicles.”

Key Reasons Driving the Emissions Gap

Analysts linked the majority of the gap to inflated estimates of the “utility factor” – the ratio of miles travelled in electric mode relative to overall mileage. The team found that only 27% of travel was done in EV mode, whereas official estimates assumed 84%.

Even, when running in electric mode, pollution levels were significantly higher than official estimates. This occurred because EV motors were not strong sufficient to operate independently, leading to engines using fossil fuels for nearly a third of the distance covered in electric mode.

Policy and Financial Consequences

According to estimates, the lowballing of PHEV emissions enabled several large carmaker groups to escape more than €5bn in fines from 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs could spend about €500 more annually in running costs than would be estimated under lab conditions.

“The strong statements that automakers often promote about their PHEV cars are obviously way off the mark,” stated a automotive analyst. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running expenses.”

Political Discussion and Industry Lobbying

Hybrid cars have lately been drawn back into policy discussions as automakers have lobbied the EU to relax CO₂ targets. A planned ban on new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and resistance from EU countries with significant automotive manufacturing.

Several high-level officials have proposed PHEVs as a potential “compromise” solution to include in the legislation.

An external energy policy specialist, who was not involved with the research, called the report a “very useful addition” after years in which parts of the car industry claimed there was too little information to properly assess real-world CO2 output.

“These findings show, without question, that the difference in official and actual PHEV energy use and CO₂ output is significantly greater than for gasoline or diesel vehicles,” the expert stated. “All policy adjustments concerning PHEVs should be implemented with utmost care and considering that data.”