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Plug-in hybrid cars produce nearly five times greater planet-heating emissions than lab-reported figures show, as per a new report.

Widening Discrepancy In Lab and Real-World Emissions

Statistics reveals that PHEVs emit just 19% less CO₂ than traditional gas and diesel vehicles, according to analysis conducted by a non-profit organization. This differs sharply with laboratory tests, which suggested a 75% reduction in pollution.

Researchers examined information from in-vehicle fuel consumption 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 lab figures, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” stated a senior analyst involved in the report. “This gap is widening and creates a serious issue. As a result, PHEVs pollute nearly as heavily as petrol cars.”

Key Factors Behind the Discrepancy

Analysts attributed the majority of the difference to overestimates of the “electric driving share” – the percentage of kilometers travelled in electric mode relative to total mileage. They found that just a quarter of travel was completed in electric mode, while lab estimates suggested 84%.

Even, when operating in EV mode, pollution amounts were well above official estimates. This occurred because electric motors were insufficiently powerful sufficient to operate independently, resulting to combustion motors burning fossil fuels for almost a third of the travel covered in electric mode.

Regulatory and Financial Implications

According to calculations, the underestimation of PHEV CO2 output allowed four large automaker groups to escape over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would spend approximately €500 extra per year in operating expenses than is assumed under laboratory tests.

“The strong statements that automakers often promote about their plug-in hybrid cars are obviously way off the mark,” commented a automotive expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are little improved than standard petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Lobbying

Hybrid cars have lately been brought again into political discussions as automakers have pressed the EU to relax CO₂ targets. A proposed prohibition on sales of new internal combustion cars in 2035 has faced intense lobbying from the car sector and resistance from EU countries with significant car industries.

Several senior politicians have proposed PHEVs as a possible “compromise” option to include in the legislation.

An external energy economics expert, who was unaffiliated with the research, called the analysis a “very useful contribution” after a long period in which segments of the car sector argued there was too little information to accurately evaluate real-world CO2 output.

“These findings show, beyond any doubt, that the gap between official and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or conventional cars,” the expert stated. “All policy changes concerning PHEVs should be implemented with utmost care and in the light of that data.”