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Plug-in hybrid cars produce nearly five times greater planet-heating pollution than official data show, as per a recent analysis.

Growing Gap In Official and Actual Emissions

Data reveals that PHEVs emit only 19% less CO₂ than traditional petrol and diesel cars, according to analysis carried out by a non-profit group. This contrasts significantly with laboratory tests, which suggested a 75% decrease in emissions.

Analysts examined data from in-vehicle energy use meters of eight hundred thousand vehicles sold in Europe from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, increased from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported figures are falling,” said a lead researcher involved in the report. “That discrepancy is growing and poses a serious problem. Consequently, PHEVs emit nearly as much as gasoline cars.”

Key Reasons Driving the Emissions Gap

Analysts attributed most of the difference to overestimates of the “utility factor” – the ratio of miles travelled in battery power compared to total mileage. They found that just 27% of driving was completed in electric mode, whereas lab assumptions assumed 84%.

Even, when running in electric mode, pollution levels were well above lab projections. This happened because EV motors were insufficiently powerful sufficient to operate independently, leading to combustion motors using gasoline for almost a third of the distance covered in electric mode.

Regulatory and Financial Consequences

Based on calculations, the lowballing of PHEV emissions enabled several major automaker companies to avoid more than €5bn in fines from 2021 and 2023, by artificially simplifying adherence with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs could pay approximately €500 extra annually in operating expenses than is assumed under laboratory conditions.

“The strong claims that manufacturers often promote about their PHEV cars are clearly far from the truth,” stated a transport analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel use, CO₂ emissions, and running expenses.”

Political Debate and Automotive Pressure

Hybrid cars have lately been drawn back into policy discussions as carmakers have lobbied the European Union to weaken CO₂ targets. A proposed prohibition on new combustion engine vehicles in 2035 has faced heavy pressure from the automotive sector and resistance from EU countries with significant car industries.

Several high-level politicians have proposed plug-in hybrids as a potential “flexibility” solution to introduce in the regulation.

An external energy economics expert, who was unaffiliated with the research, described the analysis a “highly valuable contribution” after years in which parts of the automotive sector argued there was insufficient data to accurately assess actual CO2 output.

“The results show, without question, that the gap in official and actual PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or diesel vehicles,” they said. “Any regulatory adjustments concerning PHEVs should be made with extreme care and in the light of this evidence.”