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PHEVs produce nearly five times greater planet-heating emissions than lab-reported data indicate, as per a new report.

Widening Gap Between Lab and Real-World Emissions

Data reveals that PHEVs emit just one-fifth less CO₂ than traditional gas and diesel cars, based on research conducted by a non-profit group. This contrasts sharply with laboratory estimates, which assumed a three-quarters reduction in emissions.

Analysts studied data from in-vehicle energy use monitors of 800,000 cars registered in Europe between 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from three and a half times in 2021.

“Real-world CO2 output are increasing, while lab-reported emissions are decreasing,” said a lead researcher participating in the report. “That discrepancy is growing and creates a significant issue. As a result, PHEVs emit almost as much as petrol vehicles.”

Primary Reasons Driving the Emissions Gap

Analysts linked most of the gap to overestimates of the “electric driving share” – the ratio of kilometers travelled in battery mode compared to total mileage. The team found that just 27% of driving was completed in EV mode, whereas lab estimates suggested over four-fifths.

Even, when operating in EV mode, emission amounts were well above official projections. This happened because electric motors were not strong enough to function independently, resulting to engines burning gasoline for nearly a third of the travel completed in electric mode.

Policy and Financial Implications

Based on calculations, the lowballing of PHEV CO2 output allowed several large carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could pay approximately €500 more per year in operating expenses than would be assumed under lab tests.

“The bold statements that automakers often promote about their plug-in hybrid vehicles are obviously far from the mark,” commented a automotive expert. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have lately been brought again into political discussions as automakers have pressed the EU to weaken CO₂ targets. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced heavy lobbying from the car industry and resistance from EU countries with large car industries.

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

One independent energy economics expert, who was unaffiliated with the research, called the report a “highly valuable addition” after a long period in which parts of the automotive industry argued there was insufficient data to accurately evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the difference in official and real-world PHEV energy use and CO₂ output is significantly greater than for gasoline or diesel cars,” the expert stated. “All policy changes concerning PHEVs should be made with utmost care and in the light of that evidence.”