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Plug-in hybrid electric vehicles release nearly 5x greater global warming pollution than lab-reported data show, according to a recent analysis.

Growing Gap In Lab and Real-World Emissions

Statistics reveals that PHEVs release just 19% less CO₂ than traditional gas and diesel cars, according to research conducted by a advocacy group. That differs significantly with laboratory estimates, which suggested a 75% decrease in pollution.

Analysts studied data from in-vehicle fuel consumption monitors of 800,000 vehicles registered in the EU between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while official figures are falling,” said a senior analyst involved in the report. “That gap is widening and poses a serious problem. As a result, PHEVs emit nearly as heavily as petrol cars.”

Primary Factors Driving the Discrepancy

Researchers attributed most of the difference to overestimates of the “utility factor” – the ratio of kilometers driven in electric power relative to overall mileage. The team determined that just 27% of travel was completed in EV mode, whereas lab assumptions suggested 84%.

Even, when operating in electric mode, pollution levels were significantly higher than lab estimates. That happened because EV motors were insufficiently powerful sufficient to operate independently, leading to combustion motors using fossil fuels for almost one-third of the distance completed in EV mode.

Regulatory and Financial Implications

According to calculations, the underestimation of PHEV emissions allowed several major carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs would pay about €500 extra annually in operating expenses than would be estimated under laboratory tests.

“The strong claims that manufacturers often promote about their PHEV cars are clearly far from the truth,” stated a automotive expert. “Buyers are being misled into thinking that by buying a PHEV, they are helping the planet and saving costs. In reality, PHEVs are only slightly better than standard petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating costs.”

Policy Discussion and Industry Lobbying

Hybrid cars have lately been drawn again into political discussions as automakers have pressed the EU to relax CO₂ targets. A proposed ban on new combustion engine cars in 2035 has faced intense lobbying from the automotive industry and resistance from EU countries with large car industries.

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

An external energy policy expert, who was unaffiliated with the research, called the report a “highly valuable addition” after years in which parts of the automotive sector claimed there was insufficient data to accurately assess actual emissions.

“These findings show, beyond any doubt, that the gap between official and actual PHEV fuel consumption and CO₂ output is significantly larger than for petrol or diesel cars,” they stated. “All regulatory changes concerning PHEVs should be implemented with extreme care and in the light of this data.”