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PHEVs release nearly 5x more planet-heating emissions than official figures show, as per a new report.

Growing Discrepancy Between Official and Actual CO2 Output

Data shows that PHEVs release only one-fifth lower CO₂ than conventional petrol and diesel cars, according to research carried out by a non-profit organization. That differs sharply with lab tests, which suggested a three-quarters reduction in emissions.

Analysts examined information from onboard fuel consumption meters of eight hundred thousand vehicles sold in the EU from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from 3.5 times in 2021.

“Real-world emissions are rising, while official figures are decreasing,” stated a senior analyst involved in the report. “That gap is growing and creates a serious issue. As a result, PHEVs pollute almost as heavily as petrol vehicles.”

Key Reasons Behind the Emissions Gap

Analysts attributed most of the difference to overestimates of the “electric driving share” – the percentage of kilometers driven in battery power relative to overall mileage. They determined that only 27% of travel was completed in electric mode, whereas lab assumptions assumed over four-fifths.

Additionally, when running in electric mode, pollution levels were significantly higher than official estimates. This occurred because EV motors were not strong enough to function independently, resulting to engines burning fossil fuels for almost a third of the distance completed in EV mode.

Regulatory and Financial Consequences

According to estimates, the lowballing of PHEV emissions allowed several large carmaker groups to escape over €5bn in fines between 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO₂ standards.

Furthermore, owners of PHEVs would pay approximately €500 extra annually in running costs than is assumed under laboratory tests.

“The strong statements that automakers often promote about their PHEV vehicles are obviously far from the truth,” stated a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are only slightly improved than regular petrol and diesel cars in terms of fuel use, CO₂ emissions, and running costs.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been brought again into political debates as automakers have pressed the EU to weaken CO₂ targets. A planned ban on new internal combustion vehicles in 2035 has faced heavy pressure from the car sector and resistance from member states with large automotive manufacturing.

Some senior politicians have proposed PHEVs as a potential “compromise” option to include in the regulation.

An external energy policy expert, who was unaffiliated with the research, called the report a “highly valuable addition” after years in which parts of the automotive sector claimed there was too little data to accurately assess real-world emissions.

“The results demonstrate, beyond any doubt, that the difference between lab and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or conventional cars,” the expert said. “All policy adjustments concerning PHEVs should be made with extreme care and in the light of that data.”