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PHEVs produce almost five times greater planet-heating pollution than lab-reported figures show, according to a recent analysis.

Growing Gap Between Official and Real-World CO2 Output

Data reveals that PHEVs emit only one-fifth less CO₂ than conventional petrol and diesel vehicles, according to analysis conducted by a advocacy organization. This differs sharply with laboratory tests, which assumed a three-quarters reduction in emissions.

Researchers examined data from onboard fuel consumption meters of eight hundred thousand cars sold in the EU between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official emissions are falling,” stated a lead researcher participating in the study. “This discrepancy is widening and creates a serious problem. Consequently, PHEVs emit nearly as much as gasoline cars.”

Key Factors Driving the Discrepancy

Analysts attributed the majority of the gap to overestimates of the “utility factor” – the percentage of kilometers driven in battery power compared to total mileage. The team found that just 27% of driving was done in EV mode, while official estimates suggested over four-fifths.

Even, when operating in EV mode, emission amounts were significantly higher than official estimates. This happened because electric motors were not strong sufficient to operate alone, leading to engines burning gasoline for nearly a third of the travel covered in EV mode.

Policy and Economic Consequences

Based on estimates, the lowballing of PHEV emissions enabled four large automaker groups to avoid more than €5bn in fines between 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs could pay about €500 extra per year in operating costs than is estimated under laboratory tests.

“The strong claims that automakers like to make about their plug-in hybrid cars are clearly way off the truth,” commented a automotive analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are little better than regular gas and diesel vehicles in terms of energy use, CO₂ emissions, and operating expenses.”

Policy Debate and Industry Pressure

Hybrid cars have recently been drawn back into policy discussions as automakers have lobbied the European Union to relax CO₂ targets. A proposed ban on new internal combustion cars in 2035 has faced heavy pressure from the automotive industry and opposition from EU countries with large automotive manufacturing.

Several high-level politicians have suggested plug-in hybrids as a potential “compromise” solution to introduce in the legislation.

One independent energy policy expert, who was not involved with the research, called the report a “very useful contribution” after a long period in which segments of the automotive sector claimed there was too little information to properly evaluate actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in official and actual PHEV fuel consumption and CO₂ output is much, much greater than for petrol or conventional vehicles,” they said. “All regulatory adjustments concerning PHEVs should be implemented with utmost caution and considering this evidence.”