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PHEVs release almost 5x greater global warming emissions than official figures show, according to a recent analysis.

Growing Discrepancy Between Official and Actual CO2 Output

Data shows that PHEVs emit just 19% less CO₂ than traditional gas and diesel cars, based on research carried out by a advocacy group. That contrasts significantly with lab tests, which suggested a 75% reduction in emissions.

Researchers studied information from in-vehicle fuel consumption monitors of eight hundred thousand vehicles registered in Europe between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are falling,” stated a senior researcher participating in the report. “This gap is widening and creates a significant problem. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Primary Factors Driving the Emissions Gap

Researchers linked the majority of the difference to overestimates of the “electric driving share” – the percentage of miles driven in battery power relative to total mileage. The team determined that just a quarter of driving was done in electric mode, whereas lab estimates assumed over four-fifths.

Even, when running in EV mode, pollution amounts were well above official estimates. That happened because electric motors were not strong enough to operate independently, resulting to combustion motors using fossil fuels for nearly one-third of the distance completed in EV mode.

Regulatory and Financial Implications

Based on estimates, the underestimation of PHEV emissions enabled four major carmaker groups to escape more than €5bn in fines between 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs could pay about €500 extra per year in running expenses than would be estimated under lab conditions.

“The strong statements that manufacturers like to make about their plug-in hybrid cars are clearly way off the mark,” commented a automotive expert. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are little improved than standard petrol and diesel cars in terms of energy use, CO₂ production, and operating costs.”

Political Discussion and Automotive Lobbying

Plug-in hybrid cars have lately been drawn again into political discussions as carmakers have pressed the EU to weaken CO₂ targets. A planned ban on new combustion engine cars in 2035 has faced heavy pressure from the car industry and opposition from member states with significant car industries.

Some high-level politicians have proposed plug-in hybrids as a possible “flexibility” solution to include in the regulation.

One independent energy policy specialist, who was not involved with the research, called the analysis a “very useful addition” after years in which segments of the automotive industry claimed there was insufficient data to accurately evaluate actual emissions.

“These findings demonstrate, beyond any doubt, that the difference between official and real-world PHEV energy use and CO₂ emissions is significantly greater than for gasoline or diesel vehicles,” the expert said. “Any policy changes concerning PHEVs should be made with extreme care and considering that evidence.”