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PHEVs release nearly 5x more planet-heating emissions than official figures show, according to a recent analysis.

Growing Discrepancy In Official and Actual CO2 Output

Statistics shows that PHEVs release just 19% less CO₂ than conventional petrol and diesel vehicles, based on research conducted by a non-profit organization. That contrasts significantly with laboratory tests, which assumed a three-quarters reduction in pollution.

Analysts examined data from onboard fuel consumption monitors of eight hundred thousand vehicles registered in the EU between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported figures are decreasing,” said a senior analyst participating in the study. “That gap is widening and poses a significant problem. As a result, PHEVs emit almost as heavily as gasoline cars.”

Key Factors Driving the Emissions Gap

Researchers attributed most of the gap to overestimates of the “utility factor” – the ratio of kilometers travelled in electric mode relative to overall distance. The team found that only 27% of driving was completed in electric mode, while official estimates assumed 84%.

Even, when running in electric mode, pollution levels were significantly higher than official estimates. That happened because EV motors were insufficiently powerful sufficient to function alone, resulting to engines using gasoline for nearly a third of the travel covered in electric mode.

Policy and Economic Implications

Based on calculations, the lowballing of PHEV CO2 output enabled four large carmaker companies to escape over €5bn in fines from 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could spend about €500 more per year in running expenses than would be assumed under laboratory tests.

“The strong claims that manufacturers often promote about their PHEV vehicles are obviously way off the truth,” commented a automotive analyst. “Buyers are being duped into thinking that by buying a PHEV, they are helping the environment and cutting money. In reality, PHEVs are only slightly better than regular gas and diesel cars in terms of fuel use, CO₂ production, and running costs.”

Policy Discussion and Industry Pressure

Plug-in hybrid vehicles have recently been brought back into policy debates as carmakers have pressed the EU to weaken CO₂ targets. A planned ban on new combustion engine cars in 2035 has faced intense lobbying from the car industry and resistance from EU countries with large automotive manufacturing.

Some high-level politicians have suggested PHEVs as a possible “compromise” option to introduce in the legislation.

An external energy economics specialist, who was unaffiliated with the study, described the report a “highly valuable contribution” after a long period in which segments of the automotive sector claimed there was too little data to properly assess real-world CO2 output.

“The results show, beyond any doubt, that the gap between lab and real-world PHEV energy use and CO₂ output is significantly larger than for petrol or conventional cars,” they stated. “Any policy adjustments concerning PHEVs should be implemented with extreme care and considering that evidence.”