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PHEVs emit nearly 5x greater global warming emissions than lab-reported figures show, as per a recent analysis.

Growing Discrepancy Between Lab and Real-World Emissions

Statistics shows that PHEVs emit just 19% lower CO₂ than conventional petrol and diesel cars, based on research carried out by a non-profit group. This contrasts sharply with lab tests, which suggested a 75% decrease in emissions.

Analysts examined data from in-vehicle fuel consumption meters of eight hundred thousand vehicles sold in Europe between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, up from 3.5 times in 2021.

“Actual emissions are increasing, while official figures are decreasing,” said a senior researcher participating in the report. “That discrepancy is growing and creates a significant problem. As a result, PHEVs pollute almost as much as gasoline cars.”

Key Reasons Driving the Discrepancy

Researchers attributed most of the gap to overestimates of the “utility factor” – the percentage of miles travelled in battery mode relative to overall mileage. They determined that only 27% of travel was completed in EV mode, while official estimates assumed 84%.

Additionally, when running in electric mode, emission levels were significantly higher than official projections. This occurred because electric motors were not strong enough to function alone, leading to engines using gasoline for almost one-third of the distance completed in EV mode.

Policy and Economic Implications

Based on estimates, the underestimation of PHEV emissions enabled several large automaker companies to avoid over €5bn in fines between 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs would spend approximately €500 more annually in operating expenses than would be assumed under laboratory tests.

“The bold claims that automakers often promote about their plug-in hybrid cars are clearly far from the mark,” commented a transport expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are little improved than regular petrol and diesel cars in terms of fuel use, CO₂ emissions, and running costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid cars have lately been brought back into political debates as automakers have lobbied the EU to weaken CO₂ targets. A planned ban on new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive industry and opposition from EU countries with significant car industries.

Some senior officials have proposed PHEVs as a potential “compromise” solution to introduce in the regulation.

One external 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 sector argued there was insufficient data to accurately assess real-world CO2 output.

“The results demonstrate, beyond any doubt, that the gap in official and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or conventional vehicles,” they stated. “Any regulatory changes regarding PHEVs should be made with extreme care and in the light of that evidence.”