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Plug-in hybrid cars emit nearly 5x greater planet-heating pollution than lab-reported figures indicate, as per a recent report.

Growing Discrepancy In Lab and Actual CO2 Output

Statistics shows that PHEVs emit just one-fifth less CO₂ than traditional gas and diesel cars, based on analysis carried out by a non-profit organization. This contrasts significantly with laboratory estimates, which assumed a 75% decrease in emissions.

Researchers studied data from onboard fuel consumption monitors of 800,000 vehicles registered in Europe between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are falling,” said a lead researcher involved in the study. “This discrepancy is widening and poses a serious issue. Consequently, PHEVs emit nearly as heavily as gasoline cars.”

Primary Reasons Driving the Emissions Gap

Analysts attributed most of the difference to inflated estimates of the “utility factor” – the percentage of kilometers driven in electric mode relative to overall distance. The team found that only a quarter of driving was done in electric mode, while official assumptions assumed 84%.

Additionally, when operating in EV mode, pollution amounts were significantly higher than official estimates. That occurred because electric motors were not strong sufficient to function alone, leading to combustion motors using fossil fuels for almost a third of the travel completed in EV mode.

Policy and Economic Consequences

Based on estimates, the underestimation of PHEV emissions enabled several major automaker groups to escape over €5bn in fines from 2021 and 2023, by artificially simplifying adherence with EU average fleet CO₂ targets.

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

“The strong statements that manufacturers often promote about their plug-in hybrid cars are clearly far from the mark,” commented a automotive expert. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are only slightly improved than regular gas and diesel cars in terms of fuel consumption, CO₂ emissions, and running costs.”

Political Debate and Automotive Lobbying

Hybrid cars have recently been drawn back into policy 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 car industry and opposition from member states with large car industries.

Several senior politicians have suggested PHEVs as a potential “flexibility” option to introduce in the legislation.

One external energy economics specialist, who was unaffiliated with the research, described the analysis a “highly valuable contribution” after years in which parts of the automotive sector argued there was too little information to accurately assess actual emissions.

“These findings show, beyond any doubt, that the difference between lab and actual PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or diesel vehicles,” they said. “Any policy changes regarding PHEVs should be implemented with extreme caution and considering this evidence.”