🔗 Share this article

Plug-in hybrid cars release almost five times more global warming pollution than official figures indicate, according to a new report.

Growing Gap In Lab and Actual Emissions

Statistics shows that PHEVs release only one-fifth less CO₂ than conventional petrol and diesel vehicles, based on research conducted by a non-profit group. That differs significantly with laboratory estimates, which suggested a three-quarters reduction in pollution.

Analysts studied data from in-vehicle fuel consumption monitors of 800,000 vehicles registered in the EU from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported figures are decreasing,” said a senior analyst participating in the report. “That gap is growing and poses a serious problem. As a result, PHEVs pollute nearly as heavily as petrol vehicles.”

Key Factors Behind the Emissions Gap

Researchers linked the majority of the gap to overestimates of the “electric driving share” – the percentage of miles travelled in electric power compared to total mileage. The team determined that just 27% of driving was done in electric mode, whereas lab assumptions suggested over four-fifths.

Even, when running in electric mode, emission amounts were well above official projections. That happened because electric motors were insufficiently powerful sufficient to operate independently, leading to engines burning fossil fuels for almost a third of the distance covered in electric mode.

Policy and Economic Implications

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

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

“The strong statements that manufacturers like to make about their PHEV cars are obviously far from the truth,” stated a automotive analyst. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are little better than regular gas and diesel cars in terms of energy consumption, CO₂ production, and operating costs.”

Political Debate and Industry Pressure

Hybrid vehicles have recently been brought again into policy debates as carmakers have pressed the European Union to weaken CO₂ targets. A proposed prohibition on sales of new combustion engine cars in 2035 has faced heavy pressure from the car sector and opposition from EU countries with significant car manufacturing.

Some senior politicians have proposed PHEVs as a potential “flexibility” solution to introduce in the regulation.

An external energy policy expert, who was unaffiliated with the research, described the report a “highly valuable contribution” after years in which parts of the automotive industry argued there was insufficient information to accurately assess real-world CO2 output.

“These findings show, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or diesel cars,” they stated. “Any policy adjustments concerning PHEVs should be implemented with utmost caution and in the light of that data.”