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Plug-in hybrid cars emit nearly five times more global warming pollution than official figures indicate, as per a recent analysis.

Widening Gap In Official and Real-World Emissions

Statistics reveals that PHEVs release only 19% lower CO₂ than conventional petrol and diesel cars, according to analysis carried out by a non-profit group. That differs significantly with laboratory estimates, which suggested a three-quarters decrease in emissions.

Researchers studied information from onboard fuel consumption monitors of 800,000 vehicles sold in the EU from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are decreasing,” said a senior researcher involved in the study. “This gap is growing and poses a significant problem. As a result, PHEVs emit almost as much as petrol cars.”

Key Reasons Behind the Emissions Gap

Researchers linked most of the gap to overestimates of the “utility factor” – the percentage of kilometers travelled in battery power relative to overall distance. They determined that only a quarter of travel was completed in electric mode, whereas official estimates suggested over four-fifths.

Additionally, when running in EV mode, pollution levels were significantly higher than lab projections. This occurred because electric motors were insufficiently powerful enough to operate independently, leading to engines using fossil fuels for nearly one-third of the distance completed in electric mode.

Regulatory and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output enabled four large automaker companies to avoid over €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would pay approximately €500 more per year in running costs than is estimated under laboratory conditions.

“The strong claims that automakers often promote about their plug-in hybrid vehicles are clearly far from the truth,” commented a automotive expert. “Consumers are being duped into thinking that by buying a PHEV, they are helping the planet and saving money. In reality, PHEVs are only slightly improved than regular gas and diesel cars in terms of fuel consumption, CO₂ emissions, and operating costs.”

Political Debate and Industry Pressure

Plug-in hybrid vehicles have lately been brought again into political debates as automakers have pressed the EU to weaken CO₂ targets. A proposed ban on sales of new combustion engine cars in 2035 has faced heavy pressure from the car sector and resistance from EU countries with significant car industries.

Some senior politicians have suggested PHEVs as a potential “flexibility” solution to include in the legislation.

One independent energy policy specialist, who was unaffiliated with the research, called the report a “highly valuable addition” after a long period in which segments of the automotive sector argued there was insufficient data to accurately evaluate real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the gap in official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” the expert stated. “All policy adjustments concerning PHEVs should be made with extreme caution and considering that evidence.”