🔗 Share this article

Plug-in hybrid cars emit almost 5x greater planet-heating pollution than official data indicate, as per a new analysis.

Widening Gap In Lab and Actual Emissions

Data reveals that PHEVs release only one-fifth less CO₂ than conventional petrol and diesel cars, based on research conducted by a advocacy organization. That differs sharply with lab estimates, which assumed a three-quarters decrease in pollution.

Analysts studied data from onboard fuel consumption meters of 800,000 vehicles registered in Europe from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, increased from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported figures are decreasing,” stated a senior researcher involved in the study. “That discrepancy is widening and creates a significant issue. Consequently, PHEVs pollute almost as heavily as petrol cars.”

Primary Reasons Driving the Emissions Gap

Analysts linked the majority of the gap to overestimates of the “utility factor” – the ratio of miles driven in battery mode relative to total mileage. They found that only 27% of driving was done in electric mode, while lab estimates assumed over four-fifths.

Additionally, when running in electric mode, pollution levels were well above lab projections. This happened because electric motors were not strong enough to operate alone, leading to engines using gasoline for nearly a third of the distance covered in EV mode.

Policy and Financial Consequences

According to calculations, the underestimation of PHEV emissions enabled several major carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs could pay approximately €500 more annually in operating expenses than is estimated under lab conditions.

“The bold statements that automakers like to make about their PHEV cars are obviously way off the truth,” stated a automotive analyst. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are little better than standard gas and diesel cars in terms of energy consumption, CO₂ emissions, and running expenses.”

Policy Discussion and Industry Pressure

Plug-in hybrid cars have recently been brought back into political debates as carmakers have lobbied the EU to weaken CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the car sector and opposition from member states with large car industries.

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

An external energy economics expert, who was unaffiliated with the research, called the report a “very useful addition” after years in which parts of the automotive sector claimed there was too little information to properly assess actual CO2 output.

“The results demonstrate, without question, that the gap in lab and actual PHEV energy use and CO₂ emissions is significantly greater than for petrol or conventional vehicles,” the expert said. “Any regulatory changes concerning PHEVs should be implemented with utmost caution and in the light of this evidence.”