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PHEVs release almost 5x greater global warming pollution than official figures indicate, according to a new analysis.

Widening Gap In Official and Real-World CO2 Output

Data shows that PHEVs emit just one-fifth less CO₂ than conventional gas and diesel vehicles, according to analysis carried out by a advocacy organization. This contrasts significantly with laboratory estimates, which suggested a 75% reduction in emissions.

Researchers examined data from in-vehicle fuel consumption monitors of eight hundred thousand cars sold in the EU between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are decreasing,” said a lead researcher involved in the study. “That gap is widening and creates a serious problem. Consequently, PHEVs emit nearly as much as gasoline cars.”

Primary Reasons Behind the Discrepancy

Researchers linked the majority of the difference to inflated estimates of the “utility factor” – the ratio of miles driven in electric mode relative to overall distance. The team found that just a quarter of driving was completed in EV mode, while lab estimates assumed 84%.

Even, when running in EV mode, emission amounts were significantly higher than lab projections. That occurred because EV motors were not strong enough to function independently, resulting to combustion motors burning gasoline for nearly one-third of the travel completed in electric mode.

Policy and Financial Implications

According to estimates, the underestimation of PHEV CO2 output allowed several large automaker groups to avoid more than €5bn in penalties between 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs could pay approximately €500 extra per year in running costs than would be assumed under lab tests.

“The strong claims that manufacturers often promote about their plug-in hybrid cars are clearly far from the truth,” stated a transport analyst. “Consumers are being misled into believing that by buying a PHEV, they are helping the planet and saving money. Actually, PHEVs are little better than standard gas and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have lately been brought again into political discussions as automakers have pressed the European Union to weaken CO₂ targets. A planned prohibition on new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with significant automotive manufacturing.

Some high-level officials have suggested plug-in hybrids as a possible “flexibility” option to include in the legislation.

An external energy economics specialist, who was not involved with the study, described the analysis a “very useful contribution” after a long period in which parts of the automotive sector argued there was insufficient data to accurately assess actual CO2 output.

“These findings show, beyond any doubt, that the gap between lab and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or diesel vehicles,” they stated. “Any regulatory changes regarding PHEVs should be made with utmost care and considering this evidence.”