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PHEVs produce almost 5x more planet-heating pollution than official figures show, as per a new report.

Widening Gap Between Official and Real-World CO2 Output

Data reveals that PHEVs emit just 19% lower CO₂ than traditional gas and diesel cars, based on research conducted by a non-profit organization. This differs sharply with lab estimates, which suggested a three-quarters decrease in pollution.

Researchers studied information from in-vehicle energy use monitors of 800,000 cars registered in the EU between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official figures, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported figures are falling,” said a senior analyst participating in the study. “This discrepancy is widening and poses a significant issue. As a result, PHEVs pollute almost as much as petrol vehicles.”

Key Factors Behind the Emissions Gap

Researchers linked the majority of the difference to overestimates of the “utility factor” – the percentage of kilometers travelled in electric power relative to total distance. They found that only a quarter of travel was completed in electric mode, whereas lab estimates suggested 84%.

Additionally, when operating in electric mode, pollution amounts were significantly higher than official projections. This occurred because EV motors were insufficiently powerful enough to operate independently, resulting to combustion motors using gasoline for nearly one-third of the distance covered in EV mode.

Policy and Financial Implications

According to calculations, the underestimation of PHEV CO2 output enabled four large automaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 more per year in running costs than is assumed under laboratory conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid cars are clearly far from the truth,” stated a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are little better than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating expenses.”

Political Debate and Industry Lobbying

Hybrid cars have recently been drawn back into policy discussions as carmakers have pressed the EU to relax CO₂ targets. A proposed ban on new internal combustion cars in 2035 has faced heavy lobbying from the automotive sector and resistance from member states with large car manufacturing.

Some senior politicians have proposed PHEVs as a potential “compromise” option to introduce in the legislation.

An independent energy economics specialist, who was unaffiliated with the research, described the report a “highly valuable contribution” after a long period in which parts of the automotive sector claimed there was insufficient information to properly assess real-world CO2 output.

“The results show, beyond any doubt, that the gap between official and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or diesel cars,” they said. “All regulatory adjustments regarding PHEVs should be implemented with extreme caution and in the light of that evidence.”