Plug-in Hybrid electric Cars Pollute Nearly as Much as Gasoline Cars, Study Finds

PHEVs produce almost 5x greater global warming emissions than lab-reported data indicate, as per a recent report.

Widening Gap In Lab and Real-World Emissions

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

Researchers examined data from in-vehicle fuel consumption monitors of 800,000 cars sold in the EU from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than official figures, increased from three and a half times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are decreasing,” stated a senior researcher involved in the study. “This discrepancy is widening and creates a significant issue. Consequently, PHEVs pollute nearly as heavily as gasoline cars.”

Key Reasons Behind the Discrepancy

Researchers linked most of the difference to inflated estimates of the “utility factor” – the ratio of miles driven in electric mode relative to overall mileage. They determined that just a quarter of travel was done in EV mode, whereas lab estimates suggested 84%.

Even, when operating in electric mode, emission amounts were significantly higher than lab estimates. This happened because EV motors were insufficiently powerful enough to operate alone, leading to engines burning gasoline for nearly a third of the travel covered in electric 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 simplifying adherence with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs could pay about €500 more annually in operating costs than would be estimated under laboratory conditions.

“The strong statements that automakers often promote about their PHEV vehicles are clearly way off the mark,” commented a transport analyst. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are little better than standard gas and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Lobbying

Hybrid cars have recently been brought back into policy discussions as carmakers have pressed the European Union to relax CO₂ targets. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the car industry and opposition from EU countries with large automotive manufacturing.

Several high-level politicians have suggested PHEVs as a possible “compromise” solution to introduce in the legislation.

One independent energy policy expert, who was not involved with the study, described the report a “highly valuable contribution” after a long period in which segments of the car industry argued there was insufficient data to accurately evaluate actual CO2 output.

“The results show, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or conventional cars,” the expert stated. “Any policy adjustments regarding PHEVs should be implemented with extreme care and in the light of that evidence.”