🔗 Share this article

PHEVs emit nearly five times more planet-heating emissions than lab-reported data indicate, according to a new analysis.

Growing Gap Between Lab and Real-World Emissions

Statistics reveals that PHEVs release just one-fifth less CO₂ than traditional petrol and diesel cars, based on analysis carried out by a non-profit group. That differs sharply with laboratory tests, which suggested a three-quarters decrease in emissions.

Researchers studied data from in-vehicle fuel consumption meters of 800,000 cars registered in Europe from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while official figures are decreasing,” said a senior researcher participating in the report. “This discrepancy is growing and poses a significant issue. Consequently, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Factors Behind the Discrepancy

Researchers linked the majority of the difference to overestimates of the “electric driving share” – the percentage of kilometers driven in battery power relative to overall mileage. The team determined that only 27% of driving was done in electric mode, while lab assumptions suggested 84%.

Even, when operating in electric mode, pollution levels were significantly higher than lab estimates. This happened because EV motors were not strong enough to operate independently, resulting to combustion motors burning fossil fuels for almost a third of the distance covered in EV mode.

Policy and Financial Consequences

Based on estimates, the lowballing of PHEV CO2 output enabled several large carmaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs could spend approximately €500 more annually in operating costs than would be assumed under laboratory conditions.

“The bold statements that automakers often promote about their plug-in hybrid cars are obviously far from the mark,” stated a automotive expert. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are little improved than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating expenses.”

Policy Debate and Industry Pressure

Hybrid cars have lately been brought again into political debates as carmakers have lobbied the EU to relax CO₂ standards. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with significant automotive manufacturing.

Some high-level politicians have proposed plug-in hybrids as a potential “compromise” option to include in the regulation.

An independent energy economics specialist, who was unaffiliated with the study, called the analysis a “very useful contribution” after years in which segments of the car industry argued there was insufficient information to accurately evaluate actual emissions.

“These findings show, beyond any doubt, that the gap between lab and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or diesel vehicles,” they said. “All policy adjustments regarding PHEVs should be implemented with utmost caution and in the light of this data.”