Plug in Hybrid Cars Emit Almost as Heavily as Gasoline Cars, Study Reveals

Plug-in hybrid electric vehicles produce almost 5x more global warming pollution than lab-reported data show, as per a new analysis.

Widening Gap In Official and Real-World CO2 Output

Statistics shows that PHEVs release just 19% lower CO₂ than conventional petrol and diesel cars, according to research conducted by a advocacy group. That contrasts significantly with laboratory tests, which assumed a three-quarters decrease in emissions.

Researchers studied data from in-vehicle energy use meters of eight hundred thousand vehicles sold in Europe from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, increased from three and a half times in 2021.

“Real-world emissions are increasing, while official figures are decreasing,” said a lead analyst participating in the study. “This discrepancy is growing and poses a significant issue. As a result, PHEVs emit almost as much as petrol cars.”

Key Factors Behind the Discrepancy

Researchers linked the majority of the gap to inflated estimates of the “electric driving share” – the ratio of miles travelled in electric mode relative to overall mileage. The team found that only 27% of driving was completed in EV mode, while official assumptions assumed 84%.

Additionally, when running in electric mode, pollution amounts were well above lab estimates. This happened because EV motors were insufficiently powerful enough to operate independently, leading to engines using gasoline for nearly one-third of the distance completed in electric mode.

Regulatory and Financial Implications

According to estimates, the underestimation of PHEV CO2 output enabled four major automaker companies to avoid more than €5bn in fines from 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs would pay about €500 more annually in operating costs than would be assumed under laboratory tests.

“The bold claims that manufacturers often promote about their PHEV vehicles are clearly far from the truth,” commented a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and saving money. In reality, PHEVs are only slightly better than standard gas and diesel vehicles in terms of fuel consumption, CO₂ production, and running costs.”

Policy Debate and Automotive Pressure

Plug-in hybrid cars have recently been brought back into policy discussions as automakers have pressed the EU to weaken CO₂ targets. A planned ban on new internal combustion cars in 2035 has faced heavy pressure from the car industry and opposition from member states with large automotive industries.

Several senior politicians have suggested plug-in hybrids as a potential “flexibility” solution to introduce in the regulation.

One independent energy policy specialist, who was not involved with the study, described the analysis a “very useful addition” after years in which segments of the car sector argued there was insufficient information to properly evaluate actual emissions.

“These findings demonstrate, beyond any doubt, that the gap between official and real-world PHEV energy use and CO₂ output is much, much larger than for gasoline or conventional vehicles,” the expert said. “Any policy changes regarding PHEVs should be made with extreme care and in the light of this evidence.”