Plug in Hybrid Cars Pollute Nearly as Much as Petrol Cars, Study Finds

Plug-in hybrid cars release almost 5x greater planet-heating emissions than official data indicate, as per a recent analysis.

Widening Gap In Lab and Actual CO2 Output

Data shows that PHEVs release just 19% lower CO₂ than conventional gas and diesel cars, based on analysis carried out by a non-profit organization. That differs sharply with laboratory estimates, which assumed a 75% reduction in pollution.

Analysts studied data from in-vehicle energy use monitors of 800,000 cars sold in the EU from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official estimates, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while official figures are decreasing,” said a lead researcher involved in the study. “This discrepancy is growing and poses a serious issue. Consequently, PHEVs pollute nearly as much as petrol vehicles.”

Primary Reasons Driving the Emissions Gap

Researchers linked the majority of the difference to overestimates of the “utility factor” – the ratio of miles driven in electric mode relative to total mileage. They found that just 27% of travel was completed in EV mode, whereas official estimates assumed over four-fifths.

Even, when operating in electric mode, pollution amounts were significantly higher than lab estimates. That happened because EV motors were insufficiently powerful sufficient to operate alone, leading to engines burning fossil fuels for almost one-third of the distance covered in EV mode.

Policy and Economic Implications

Based on estimates, the lowballing of PHEV CO2 output allowed four major automaker companies to avoid over €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would spend about €500 more per year in running expenses than would be assumed under laboratory conditions.

“The bold statements that automakers often promote about their plug-in hybrid cars are obviously way off the truth,” commented a transport analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly better than regular gas and diesel cars in terms of energy consumption, CO₂ emissions, and running costs.”

Political Debate and Automotive Lobbying

Hybrid vehicles have lately been brought again into policy debates as automakers have lobbied the EU to relax CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the automotive industry and opposition from EU countries with significant car industries.

Some senior politicians have proposed plug-in hybrids as a possible “flexibility” option to include in the legislation.

An independent energy policy specialist, who was unaffiliated with the research, described the report a “very useful addition” after years in which segments of the automotive sector claimed there was too little data to properly evaluate real-world CO2 output.

“The results demonstrate, without question, that the difference in official and real-world PHEV fuel consumption and CO₂ output is much, much greater than for petrol or conventional cars,” they said. “Any policy adjustments regarding PHEVs should be made with extreme care and in the light of that evidence.”