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PHEVs release nearly 5x greater global warming pollution than lab-reported figures show, according to a new analysis.

Widening Gap In Lab and Actual Emissions

Data shows that PHEVs release only one-fifth lower CO₂ than traditional petrol and diesel vehicles, according to research carried out by a non-profit organization. That differs sharply with lab tests, which suggested a three-quarters decrease in emissions.

Analysts examined information from in-vehicle fuel consumption monitors of eight hundred thousand vehicles sold in the EU from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while lab-reported emissions are falling,” stated a senior analyst participating in the study. “That discrepancy is growing and poses a significant problem. Consequently, PHEVs emit almost as heavily as petrol cars.”

Key Factors Driving the Emissions Gap

Analysts linked the majority of the gap to inflated estimates of the “electric driving share” – the percentage of miles driven in battery mode compared to overall mileage. They determined that only a quarter of travel was completed in electric mode, while lab assumptions suggested over four-fifths.

Even, when running in EV mode, pollution amounts were well above official projections. This occurred because electric motors were not strong sufficient to operate alone, resulting to engines burning fossil fuels for nearly a third of the travel completed in electric mode.

Regulatory and Economic Implications

According to calculations, the lowballing of PHEV emissions allowed four large automaker companies to avoid more than €5bn in penalties between 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs would pay about €500 more per year in operating costs than would be assumed under laboratory tests.

“The strong statements that manufacturers often promote about their plug-in hybrid vehicles are obviously far from the mark,” commented a automotive analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving costs. Actually, PHEVs are little improved than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and running expenses.”

Policy Discussion and Automotive Lobbying

Hybrid cars have lately been drawn back into policy discussions as automakers have pressed the European Union to relax CO₂ targets. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with large car manufacturing.

Several high-level officials have proposed PHEVs as a potential “flexibility” option to introduce in the legislation.

An external energy economics expert, who was not involved with the study, called the analysis a “very useful addition” after a long period in which segments of the car industry claimed there was insufficient data to properly assess actual emissions.

“The results show, without question, that the gap between official and real-world PHEV fuel consumption and CO₂ output is much, much larger than for petrol or conventional vehicles,” they stated. “Any policy changes concerning PHEVs should be made with utmost caution and in the light of this data.”