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PHEVs emit almost 5x greater planet-heating pollution than official figures show, according to a new report.

Widening Gap Between Lab and Actual CO2 Output

Statistics reveals that PHEVs emit only 19% less CO₂ than traditional gas and diesel cars, according to analysis carried out by a advocacy group. This contrasts sharply with laboratory tests, which suggested a 75% decrease in pollution.

Researchers studied information from in-vehicle energy use meters of 800,000 cars registered in the EU from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, up from three and a half times in 2021.

“Actual emissions are increasing, while official emissions are decreasing,” said a lead analyst involved in the report. “That gap is growing and poses a serious issue. Consequently, PHEVs emit almost as heavily as gasoline cars.”

Key Factors Driving the Discrepancy

Analysts attributed most of the difference to overestimates of the “electric driving share” – the percentage of miles driven in battery power compared to overall mileage. They determined that just a quarter of driving was done in EV mode, whereas lab estimates assumed over four-fifths.

Additionally, when running in electric mode, pollution levels were well above official projections. This occurred because electric motors were insufficiently powerful enough to operate alone, leading to combustion motors burning gasoline for nearly a third of the travel completed in electric mode.

Policy and Economic Consequences

According to calculations, the lowballing of PHEV CO2 output allowed four major automaker groups to avoid over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs could pay about €500 more per year in running expenses than is assumed under laboratory conditions.

“The strong claims that automakers often promote about their PHEV cars are clearly way off the mark,” commented a automotive analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving costs. In reality, PHEVs are little improved than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and operating costs.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have recently been brought back into policy discussions as automakers have lobbied the EU to relax CO₂ standards. A planned prohibition on new combustion engine cars in 2035 has faced heavy lobbying from the automotive sector and opposition from EU countries with significant car industries.

Some senior officials have proposed plug-in hybrids as a possible “flexibility” solution to include in the regulation.

An external energy policy specialist, who was not involved with the study, described the report a “highly valuable addition” after a long period in which parts of the automotive industry argued there was too little information to accurately assess real-world CO2 output.

“These findings demonstrate, without question, that the gap between lab and actual PHEV energy use and CO₂ emissions is much, much larger than for petrol or conventional vehicles,” they stated. “Any policy adjustments regarding PHEVs should be implemented with utmost care and in the light of this evidence.”