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PHEVs release almost 5x more global warming pollution than official data indicate, as per a recent report.

Widening Discrepancy Between Lab and Real-World CO2 Output

Data shows that PHEVs emit only 19% lower CO₂ than conventional gas and diesel cars, according to research conducted by a advocacy group. This contrasts significantly with laboratory tests, which suggested a three-quarters decrease in emissions.

Researchers studied data from in-vehicle energy use monitors of eight hundred thousand vehicles sold in the EU from 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, increased from three and a half times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are falling,” said a lead analyst participating in the report. “This discrepancy is growing and poses a significant problem. As a result, PHEVs pollute nearly as much as petrol cars.”

Primary Factors Driving the Emissions Gap

Researchers attributed most of the difference to overestimates of the “electric driving share” – the percentage of kilometers travelled in electric power compared to total distance. They found that only a quarter of driving was completed in electric mode, while lab assumptions assumed over four-fifths.

Additionally, when running in EV mode, emission amounts were significantly higher than official projections. That happened because electric motors were insufficiently powerful enough to function alone, leading to engines burning fossil fuels for almost one-third of the distance completed in electric mode.

Policy and Economic Implications

Based on calculations, the underestimation of PHEV CO2 output allowed several large automaker groups to escape over €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ standards.

Furthermore, owners of PHEVs could pay about €500 extra annually in running expenses than is estimated under laboratory tests.

“The bold statements that manufacturers often promote about their plug-in hybrid vehicles are obviously way off the mark,” stated a transport expert. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of fuel use, CO₂ emissions, and running costs.”

Political Debate and Automotive Lobbying

Plug-in hybrid cars have recently been drawn back into political discussions as carmakers have pressed the European Union to relax CO₂ targets. A proposed ban on new internal combustion vehicles in 2035 has faced heavy lobbying from the car sector and resistance from member states with significant car manufacturing.

Some senior officials have suggested PHEVs as a potential “compromise” option to introduce in the legislation.

An independent energy economics expert, who was not involved with the research, described the analysis a “very useful addition” after a long period in which segments of the automotive sector argued there was insufficient information to properly evaluate actual CO2 output.

“The results show, beyond any doubt, that the difference in lab and real-world PHEV energy use and CO₂ emissions is significantly greater than for gasoline or conventional cars,” the expert stated. “Any policy adjustments regarding PHEVs should be made with utmost care and in the light of that evidence.”