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Plug-in hybrid cars produce almost 5x greater global warming emissions than lab-reported data show, as per a recent analysis.

Widening Discrepancy Between Official and Real-World Emissions

Statistics reveals that PHEVs release just one-fifth lower CO₂ than traditional petrol and diesel vehicles, based on research carried out by a advocacy organization. That differs significantly with laboratory tests, which assumed a 75% decrease in pollution.

Researchers examined data from in-vehicle energy use meters of eight hundred thousand vehicles registered in Europe from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official estimates, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while official emissions are falling,” said a lead analyst involved in the report. “That discrepancy is widening and creates a serious problem. Consequently, PHEVs pollute nearly as much as gasoline cars.”

Key Factors Behind the Discrepancy

Researchers linked the majority of the gap to inflated estimates of the “electric driving share” – the percentage of miles driven in battery power compared to overall mileage. The team determined that just 27% of driving was completed in EV mode, while lab assumptions suggested over four-fifths.

Additionally, when running in EV mode, emission levels were significantly higher than official estimates. This happened because EV motors were insufficiently powerful enough to operate independently, resulting to engines using fossil fuels for almost one-third of the travel completed in electric mode.

Policy and Financial Implications

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

Furthermore, owners of PHEVs could spend approximately €500 more per year in running expenses than is assumed under laboratory tests.

“The strong statements that manufacturers often promote about their PHEV cars are clearly far from the truth,” commented a transport analyst. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are little better than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and operating expenses.”

Policy Debate and Automotive Pressure

Plug-in hybrid vehicles have lately been brought back into political debates as carmakers have lobbied the EU to weaken CO₂ targets. A planned ban on new internal combustion cars in 2035 has faced intense lobbying from the car industry and resistance from EU countries with significant car manufacturing.

Some senior officials have proposed plug-in hybrids as a possible “flexibility” option to introduce in the legislation.

An external energy economics expert, who was not involved with the study, described the report a “highly valuable contribution” after years in which segments of the car industry claimed there was insufficient information to properly evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the difference between official and actual PHEV energy use and CO₂ emissions is much, much greater than for petrol or conventional vehicles,” they stated. “Any policy changes regarding PHEVs should be implemented with utmost caution and considering this evidence.”