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Plug-in hybrid electric vehicles produce almost 5x more global warming pollution than lab-reported data show, as per a recent analysis.

Widening Gap Between Official and Real-World CO2 Output

Data shows that PHEVs emit just one-fifth lower CO₂ than traditional gas and diesel cars, according to analysis conducted by a non-profit group. That contrasts significantly with laboratory estimates, which suggested a three-quarters decrease in pollution.

Analysts studied information from in-vehicle fuel consumption meters of 800,000 cars registered in the EU between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, increased from 3.5 times in 2021.

“Real-world emissions are rising, while official emissions are falling,” stated a senior analyst participating in the report. “That gap is widening and poses a significant issue. As a result, PHEVs emit almost as heavily as gasoline vehicles.”

Key Reasons Driving the Emissions Gap

Analysts attributed most of the gap to overestimates of the “utility factor” – the percentage of kilometers travelled in electric mode compared to overall distance. They determined that only a quarter of travel was done in EV mode, while lab assumptions assumed over four-fifths.

Even, when operating in electric mode, pollution amounts were well above lab estimates. This occurred because electric motors were not strong enough to function alone, resulting to engines burning gasoline for nearly one-third of the travel covered in EV mode.

Regulatory and Financial Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled several large carmaker companies to escape more than €5bn in fines from 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs would pay approximately €500 extra per year in operating expenses than would be assumed under lab conditions.

“The bold statements that manufacturers often promote about their plug-in hybrid vehicles are obviously far from the mark,” commented a transport expert. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel consumption, CO₂ production, and running costs.”

Policy Debate and Automotive Pressure

Hybrid cars have recently been brought again into policy debates as automakers have lobbied the EU to relax CO₂ standards. A planned ban on sales of new combustion engine cars in 2035 has faced intense pressure from the car industry and resistance from member states with large car manufacturing.

Several high-level politicians have proposed PHEVs as a potential “compromise” solution to introduce in the regulation.

One independent energy economics expert, who was unaffiliated with the study, described the analysis a “very useful addition” after years in which segments of the automotive industry claimed there was too little information to properly assess actual CO2 output.

“These findings demonstrate, beyond any doubt, that the gap between lab and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or diesel vehicles,” they stated. “Any policy adjustments concerning PHEVs should be implemented with extreme care and in the light of this evidence.”