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Plug-in hybrid electric vehicles release nearly five times greater global warming pollution than official figures indicate, as per a recent report.

Widening Discrepancy In Lab and Real-World CO2 Output

Statistics shows that PHEVs emit only 19% lower CO₂ than traditional petrol and diesel vehicles, according to research conducted by a non-profit group. That differs significantly with laboratory tests, which suggested a three-quarters reduction in emissions.

Analysts studied information from in-vehicle fuel consumption monitors of 800,000 vehicles registered in Europe from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, increased from three and a half times in 2021.

“Actual emissions are rising, while lab-reported figures are decreasing,” stated a senior analyst participating in the study. “That discrepancy is widening and creates a significant problem. Consequently, PHEVs emit nearly as much as petrol cars.”

Primary Factors Driving the Emissions Gap

Analysts linked most of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in electric mode compared to overall mileage. The team found that just 27% of driving was completed in electric mode, whereas lab assumptions assumed over four-fifths.

Even, when running in EV mode, pollution amounts were significantly higher than official estimates. This occurred because electric motors were insufficiently powerful sufficient to function alone, resulting to engines burning gasoline for nearly a third of the travel completed in electric mode.

Policy and Financial Implications

According to calculations, the underestimation of PHEV emissions allowed four large carmaker groups to escape over €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs would pay about €500 more per year in running expenses than is estimated under lab tests.

“The strong claims that automakers like to make about their plug-in hybrid vehicles are clearly far from the truth,” stated a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are only slightly better than standard petrol and diesel cars in terms of fuel consumption, CO₂ production, and running costs.”

Policy Debate and Automotive Pressure

Plug-in hybrid vehicles have lately been brought again into political discussions as carmakers have pressed the European Union to weaken CO₂ standards. A proposed prohibition on new combustion engine vehicles in 2035 has faced intense pressure from the automotive industry and resistance from EU countries with significant automotive manufacturing.

Some high-level politicians have proposed PHEVs as a potential “compromise” option to include in the legislation.

An external energy economics specialist, who was not involved with the research, called the analysis a “very useful addition” after a long period in which parts of the car industry claimed there was insufficient information to properly assess real-world emissions.

“These findings demonstrate, beyond any doubt, that the difference in lab and actual PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or conventional cars,” they stated. “All regulatory adjustments regarding PHEVs should be implemented with extreme care and in the light of that evidence.”