🔗 Share this article

PHEVs emit almost five times more planet-heating emissions than official figures show, according to a recent analysis.

Growing Discrepancy Between Lab and Real-World CO2 Output

Data shows that PHEVs emit just one-fifth less CO₂ than conventional gas and diesel cars, according to analysis conducted by a advocacy organization. That differs sharply with laboratory estimates, which suggested a three-quarters reduction in pollution.

Analysts studied data from in-vehicle energy use monitors of eight hundred thousand vehicles sold in Europe from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, increased from three and a half times in 2021.

“Real-world CO2 output are increasing, while official figures are decreasing,” stated a senior analyst participating in the report. “That gap is growing and poses a serious problem. As a result, PHEVs emit nearly as much as petrol vehicles.”

Key Reasons Behind the Emissions Gap

Researchers attributed most of the gap to overestimates of the “utility factor” – the ratio of kilometers travelled in battery power compared to overall mileage. The team found that just a quarter of driving was done in electric mode, whereas official estimates suggested 84%.

Even, when running in EV mode, pollution levels were well above official projections. That happened because electric motors were insufficiently powerful sufficient to function alone, leading to engines burning fossil fuels for nearly one-third of the distance covered in EV mode.

Policy and Financial Consequences

According to estimates, the underestimation of PHEV CO2 output allowed four major carmaker companies to escape over €5bn in fines from 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would pay approximately €500 more per year in operating costs than would be assumed under laboratory tests.

“The bold statements that automakers like to make about their plug-in hybrid cars are obviously far from the truth,” commented a transport analyst. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Debate and Industry Pressure

Plug-in hybrid vehicles have lately been brought again into political discussions as automakers have pressed the EU to weaken CO₂ standards. A proposed prohibition on new internal combustion cars in 2035 has faced intense lobbying from the automotive industry and resistance from member states with large automotive manufacturing.

Several senior politicians have suggested plug-in hybrids as a possible “compromise” solution to include in the regulation.

An external energy policy specialist, who was not involved with the study, described the analysis a “very useful contribution” after a long period in which segments of the car industry argued there was too little data to properly evaluate real-world emissions.

“The results demonstrate, beyond any doubt, that the gap in lab and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” they stated. “Any policy adjustments regarding PHEVs should be made with utmost care and in the light of that data.”