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PHEVs emit almost five times more global warming pollution than lab-reported figures show, as per a new analysis.

Widening Discrepancy In Official and Real-World CO2 Output

Data reveals that PHEVs release only 19% less CO₂ than conventional gas and diesel cars, according to analysis carried out by a advocacy group. That contrasts sharply with lab estimates, which suggested a 75% decrease in emissions.

Researchers studied information from in-vehicle energy use meters of eight hundred thousand vehicles registered in the EU from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, up from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” stated a lead analyst involved in the study. “This discrepancy is growing and creates a serious problem. Consequently, PHEVs emit nearly as much as petrol vehicles.”

Primary Factors Behind the Emissions Gap

Analysts attributed the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers travelled in battery mode compared to overall mileage. The team found that just 27% of travel was done in electric mode, while lab estimates suggested over four-fifths.

Additionally, when running in EV mode, pollution amounts were well above lab estimates. This occurred because electric motors were not strong sufficient to function alone, leading to engines burning fossil fuels for nearly a third of the travel completed in EV mode.

Policy and Financial Consequences

According to calculations, the lowballing of PHEV emissions enabled several major automaker companies to escape more than €5bn in penalties from 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would pay about €500 extra per year in running costs than would be estimated under lab tests.

“The strong claims that manufacturers often promote about their plug-in hybrid vehicles are clearly far from the truth,” stated a automotive analyst. “Consumers are being duped into thinking that by buying a PHEV, they are helping the environment and saving costs. In reality, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of energy use, CO₂ emissions, and running costs.”

Political Discussion and Automotive Pressure

Plug-in hybrid vehicles have recently been brought back into policy discussions as carmakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on sales of new combustion engine cars in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with large automotive industries.

Several high-level officials have proposed PHEVs as a possible “compromise” option to include in the legislation.

An external energy policy expert, who was not involved with the study, described the report a “very useful addition” after years in which parts of the car sector argued there was insufficient data to properly assess actual CO2 output.

“These findings demonstrate, beyond any doubt, that the gap in official and actual PHEV energy use and CO₂ emissions is significantly greater than for petrol or diesel vehicles,” they said. “All policy adjustments regarding PHEVs should be implemented with utmost caution and in the light of that data.”