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Plug-in hybrid electric vehicles emit nearly five times more planet-heating pollution than lab-reported data indicate, as per a recent report.

Widening Gap Between Lab and Real-World Emissions

Data reveals that PHEVs emit only 19% lower CO₂ than traditional gas and diesel vehicles, according to analysis carried out by a advocacy group. That contrasts sharply with laboratory tests, which assumed a three-quarters decrease in pollution.

Analysts studied data from in-vehicle energy use monitors of eight hundred thousand vehicles sold in Europe from 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, increased from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported emissions are decreasing,” stated a senior analyst participating in the report. “This gap is widening and poses a significant problem. Consequently, PHEVs emit nearly as much as petrol vehicles.”

Key Reasons Driving the Discrepancy

Analysts attributed most of the difference to overestimates of the “electric driving share” – the ratio of miles driven in electric power relative to total distance. They found that just a quarter of driving was completed in electric mode, whereas official assumptions assumed 84%.

Additionally, when running in EV mode, pollution amounts were significantly higher than official projections. That happened because EV motors were insufficiently powerful enough to operate independently, resulting to engines burning fossil fuels for almost one-third of the distance covered in electric mode.

Policy and Financial Implications

According to calculations, the underestimation of PHEV emissions allowed four major automaker companies to escape over €5bn in fines between 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs would spend approximately €500 extra per year in operating expenses than is estimated under laboratory tests.

“The strong claims that manufacturers like to make about their plug-in hybrid cars are obviously way off the truth,” stated a transport expert. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are little improved than regular petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and running expenses.”

Political Debate and Industry Lobbying

Hybrid vehicles have lately been drawn back into political discussions as carmakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on sales of new internal combustion cars in 2035 has faced intense pressure from the automotive industry and resistance from member states with large automotive industries.

Some high-level officials have proposed plug-in hybrids as a potential “compromise” solution to include in the regulation.

One external energy economics expert, who was unaffiliated with the study, called the report a “highly valuable contribution” after years in which segments of the automotive sector argued there was too little information to properly assess actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference between lab and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional vehicles,” they said. “Any policy adjustments regarding PHEVs should be implemented with extreme caution and considering this evidence.”