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Plug-in hybrid electric vehicles emit nearly five times more planet-heating pollution than lab-reported data indicate, as per a recent analysis.

Growing Discrepancy Between Official and Actual CO2 Output

Data shows that PHEVs release only one-fifth less CO₂ than conventional gas and diesel vehicles, based on research conducted by a advocacy organization. This contrasts significantly with laboratory tests, which suggested a three-quarters reduction in pollution.

Researchers examined information from in-vehicle energy use monitors of eight hundred thousand cars sold in the EU between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official emissions are falling,” said a senior analyst involved in the study. “This gap is growing and poses a serious issue. As a result, PHEVs emit almost as heavily as gasoline vehicles.”

Primary Reasons Driving the Emissions Gap

Analysts attributed most of the gap to inflated estimates of the “utility factor” – the ratio of kilometers driven in electric mode relative to overall mileage. The team found that only a quarter of driving was completed in electric mode, whereas official assumptions assumed over four-fifths.

Even, when running in EV mode, emission levels were well above official projections. This happened because EV motors were not strong enough to function independently, leading to engines burning fossil fuels for almost one-third of the travel covered in EV mode.

Regulatory and Financial Implications

Based on estimates, the underestimation of PHEV CO2 output allowed four major carmaker groups to avoid more than €5bn in fines from 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ targets.

Additionally, owners of PHEVs would pay about €500 extra annually in running costs than is assumed under lab conditions.

“The bold claims that manufacturers often promote about their PHEV cars are clearly way off the truth,” commented a automotive expert. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are little better than standard petrol and diesel cars in terms of energy consumption, CO₂ emissions, and running expenses.”

Political Discussion and Industry Pressure

Hybrid cars have lately been drawn again into political debates as automakers have lobbied the EU to relax CO₂ targets. A proposed ban on new internal combustion cars in 2035 has faced intense lobbying from the car sector and resistance from EU countries with large car manufacturing.

Some senior politicians have suggested plug-in hybrids as a possible “flexibility” solution to introduce in the regulation.

An independent energy policy specialist, who was unaffiliated with the study, described the analysis a “highly valuable addition” after a long period in which segments of the car industry claimed there was insufficient information to properly assess actual CO2 output.

“The results demonstrate, beyond any doubt, that the gap between lab and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or conventional cars,” the expert stated. “Any regulatory adjustments regarding PHEVs should be implemented with extreme care and in the light of that evidence.”