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Plug-in hybrid cars emit almost five times greater global warming emissions than lab-reported data show, as per a recent report.

Growing Discrepancy In Lab and Real-World CO2 Output

Data reveals that PHEVs emit just 19% less CO₂ than conventional gas and diesel cars, according to analysis conducted by a non-profit group. That contrasts significantly with lab tests, which assumed a three-quarters reduction in pollution.

Analysts examined information from onboard fuel consumption meters of 800,000 vehicles sold in the EU from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, increased from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” stated a lead researcher participating in the report. “This discrepancy is growing and creates a significant problem. Consequently, PHEVs emit almost as heavily as gasoline cars.”

Primary Factors Driving the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “utility factor” – the percentage of kilometers travelled in electric power compared to overall distance. The team found that just 27% of travel was completed in EV mode, whereas lab estimates assumed over four-fifths.

Additionally, when running in electric mode, emission amounts were significantly higher than official projections. This happened because EV motors were not strong enough to function alone, leading to engines burning gasoline for almost a third of the distance covered in EV mode.

Policy and Financial Consequences

According to calculations, the underestimation of PHEV CO2 output enabled several large carmaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could spend about €500 extra annually in running costs than would be assumed under lab tests.

“The strong statements that automakers like to make about their PHEV cars are obviously way off the mark,” stated a automotive analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the environment and cutting money. Actually, PHEVs are only slightly improved than standard gas and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Discussion and Industry Pressure

Hybrid cars have recently been brought back into policy discussions as automakers have pressed the EU to weaken CO₂ standards. A planned prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the automotive industry and resistance from EU countries with significant car industries.

Some high-level politicians have suggested PHEVs as a potential “flexibility” option to include in the regulation.

One external energy economics expert, who was not involved with the research, called the analysis a “highly valuable addition” after years in which segments of the car industry argued there was insufficient data to properly assess actual emissions.

“These findings show, beyond any doubt, that the gap in official and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or diesel vehicles,” they stated. “Any regulatory changes concerning PHEVs should be made with utmost care and considering this data.”