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Plug-in hybrid cars release nearly five times more planet-heating emissions than official data show, as per a new report.

Growing Gap In Lab and Actual CO2 Output

Statistics shows that PHEVs release only one-fifth less CO₂ than traditional petrol and diesel cars, based on analysis carried out by a advocacy group. This differs significantly with lab tests, which assumed a three-quarters decrease in emissions.

Researchers studied data from in-vehicle energy use meters of 800,000 cars sold in the EU between 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, up from three and a half times in 2021.

“Real-world emissions are increasing, while official emissions are decreasing,” stated a lead researcher involved in the report. “That gap is growing and creates a serious problem. As a result, PHEVs emit almost as heavily as petrol vehicles.”

Key Reasons Driving the Emissions Gap

Analysts attributed the majority of the difference to overestimates of the “electric driving share” – the percentage of kilometers travelled in battery mode compared to total mileage. The team determined that just 27% of travel was done in EV mode, whereas official assumptions assumed over four-fifths.

Additionally, when running in electric mode, emission amounts were well above lab projections. That happened because EV motors were insufficiently powerful enough to operate alone, resulting to combustion motors burning gasoline for almost a third of the distance completed in EV mode.

Regulatory and Economic Consequences

Based on calculations, the lowballing of PHEV emissions enabled several large automaker companies to avoid more than €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ targets.

Additionally, owners of PHEVs would pay approximately €500 extra per year in operating expenses than would be assumed under lab tests.

“The bold statements that manufacturers like to make about their PHEV vehicles are clearly way off the mark,” stated a automotive expert. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving costs. In reality, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy use, CO₂ production, and running costs.”

Policy Discussion and Automotive Lobbying

Hybrid cars have lately been brought back into political discussions as carmakers have lobbied the European Union to weaken CO₂ targets. A planned ban on new combustion engine vehicles in 2035 has faced intense pressure from the car sector and resistance from EU countries with significant automotive industries.

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

An external energy economics expert, who was not involved with the research, described the analysis a “highly valuable contribution” after a long period in which parts of the automotive sector argued there was insufficient data to accurately evaluate actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in lab and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or conventional vehicles,” the expert said. “Any regulatory adjustments concerning PHEVs should be implemented with extreme care and in the light of this data.”