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Plug-in hybrid cars produce almost 5x more planet-heating emissions than lab-reported data indicate, as per a new analysis.

Widening Gap In Lab and Real-World CO2 Output

Data reveals that PHEVs release only one-fifth less CO₂ than traditional gas and diesel cars, based on research conducted by a advocacy organization. This contrasts sharply with laboratory estimates, which assumed a three-quarters reduction in emissions.

Analysts studied data from onboard energy use meters of 800,000 cars sold in the EU between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five 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 analyst participating in the study. “That gap is growing and creates a significant issue. Consequently, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Factors Driving the Discrepancy

Analysts attributed most of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers driven in electric mode compared to overall distance. The team found that just a quarter of travel was done in EV mode, whereas lab assumptions assumed 84%.

Additionally, when running in EV mode, pollution amounts were well above official projections. That occurred because electric motors were not strong enough to function independently, resulting to combustion motors using gasoline for nearly one-third of the distance completed in EV mode.

Policy and Economic Consequences

According to calculations, the lowballing of PHEV emissions enabled several large automaker groups to escape over €5bn in penalties from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would pay about €500 more annually in running costs than is assumed under lab conditions.

“The strong statements that manufacturers like to make about their plug-in hybrid vehicles are clearly way off the truth,” commented a transport analyst. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are little improved than standard petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and running costs.”

Political Debate and Automotive Pressure

Plug-in hybrid vehicles have recently been drawn back into political discussions as carmakers have lobbied the EU to weaken CO₂ standards. A proposed ban on sales of new internal combustion cars in 2035 has faced intense pressure from the automotive industry and opposition from member states with significant automotive manufacturing.

Several senior officials have suggested PHEVs as a possible “compromise” solution to introduce in the regulation.

One independent energy economics expert, who was unaffiliated with the research, called the report a “very useful addition” after a long period in which segments of the automotive industry claimed there was too little information to properly evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the gap between official and real-world PHEV energy use and CO₂ output is much, much larger than for petrol or diesel vehicles,” the expert said. “All regulatory changes concerning PHEVs should be made with utmost caution and considering this data.”