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PHEVs emit nearly five times more planet-heating pollution than lab-reported data indicate, as per a recent analysis.

Growing Gap Between Lab and Actual Emissions

Data reveals that PHEVs release just 19% lower CO₂ than traditional petrol and diesel vehicles, based on analysis conducted by a advocacy group. That contrasts sharply with lab tests, which assumed a 75% reduction in emissions.

Researchers examined data from in-vehicle energy use meters of eight hundred thousand vehicles sold in Europe between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from 3.5 times in 2021.

“Actual emissions are rising, while official emissions are falling,” said a lead researcher participating in the report. “This gap is growing and poses a serious issue. Consequently, PHEVs pollute nearly as heavily as gasoline vehicles.”

Primary Reasons Behind the Discrepancy

Researchers attributed the majority of the difference to inflated estimates of the “electric driving share” – the ratio of miles travelled in electric power compared to overall mileage. They found that just a quarter of travel was completed in electric mode, whereas lab estimates suggested over four-fifths.

Additionally, when running in electric mode, emission amounts were well above official estimates. This happened because EV motors were insufficiently powerful sufficient to operate alone, resulting to combustion motors burning fossil fuels for almost a third of the distance covered in EV mode.

Policy and Financial Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled several large automaker groups to avoid over €5bn in penalties from 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs could pay about €500 more annually in running costs than is estimated under lab conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid vehicles are clearly way off the mark,” stated a transport expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of fuel use, CO₂ emissions, and operating expenses.”

Political Debate and Automotive Lobbying

Plug-in hybrid cars have lately been drawn back into political debates as carmakers have pressed the European Union to relax CO₂ targets. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced intense pressure from the automotive sector and opposition from member states with significant automotive industries.

Several high-level officials have proposed plug-in hybrids as a potential “flexibility” option to include in the regulation.

An external energy economics specialist, who was unaffiliated with the study, described the report a “very useful addition” after years in which parts of the automotive industry claimed there was insufficient data to accurately evaluate real-world CO2 output.

“These findings show, without question, that the gap between official and actual PHEV energy use and CO₂ emissions is significantly larger than for gasoline or diesel vehicles,” they stated. “Any policy changes regarding PHEVs should be implemented with extreme caution and considering this data.”