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PHEVs release almost five times more global warming emissions than official figures show, according to a recent report.

Growing Gap In Lab and Actual Emissions

Data reveals that PHEVs emit only 19% less CO₂ than traditional petrol and diesel cars, based on research conducted by a non-profit group. This contrasts significantly with lab tests, which suggested a 75% decrease in pollution.

Analysts studied information from in-vehicle fuel consumption monitors of eight hundred thousand vehicles sold in the EU from 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are falling,” stated a senior researcher participating in the study. “This discrepancy is growing and poses a significant issue. As a result, PHEVs emit almost as heavily as petrol vehicles.”

Primary Factors Driving the Emissions Gap

Analysts linked the majority of the difference to overestimates of the “electric driving share” – the percentage of kilometers driven in battery mode relative to overall mileage. The team determined that only 27% of driving was done in electric mode, whereas lab estimates suggested 84%.

Even, when operating in EV mode, pollution levels were well above official estimates. This occurred because electric motors were insufficiently powerful enough to operate alone, leading to combustion motors burning fossil fuels for almost one-third of the distance covered in EV mode.

Regulatory and Financial Consequences

According to calculations, the lowballing of PHEV emissions allowed several major carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would pay about €500 extra per year in running expenses than would be assumed under laboratory tests.

“The strong statements that automakers often promote about their PHEV vehicles are clearly far from the mark,” commented a transport analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are little better than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and operating costs.”

Policy Debate and Industry Lobbying

Plug-in hybrid cars have recently been brought back into policy discussions as carmakers have pressed the EU to relax CO₂ targets. A planned ban on new combustion engine cars in 2035 has faced intense lobbying from the car industry and resistance from EU countries with significant car industries.

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

An external energy economics expert, who was not involved with the research, described the report a “very useful addition” after a long period in which parts of the car sector claimed there was insufficient data to properly evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the difference between lab and actual PHEV energy use and CO₂ output is much, much larger than for gasoline or conventional vehicles,” the expert stated. “All regulatory adjustments concerning PHEVs should be implemented with extreme caution and considering this data.”