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PHEVs produce almost 5x more planet-heating pollution than lab-reported figures show, as per a new analysis.

Widening Gap In Official and Actual CO2 Output

Data reveals that PHEVs emit only 19% less CO₂ than traditional gas and diesel cars, based on analysis carried out by a non-profit organization. This differs significantly with lab estimates, which assumed a 75% decrease in emissions.

Researchers studied data from onboard fuel consumption meters of eight hundred thousand cars registered in Europe between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, up from 3.5 times in 2021.

“Actual CO2 output are rising, while official figures are decreasing,” stated a lead analyst involved in the report. “This discrepancy is widening and creates a significant issue. Consequently, PHEVs emit nearly as much as petrol cars.”

Key Reasons Driving the Emissions Gap

Researchers linked most of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in battery power relative to overall mileage. They found that just a quarter of travel was done in electric mode, whereas lab assumptions suggested over four-fifths.

Additionally, when operating in electric mode, emission amounts were well above lab estimates. That happened because electric motors were not strong enough to function alone, leading to combustion motors burning fossil fuels for nearly one-third of the travel completed in EV mode.

Regulatory and Economic Implications

According to estimates, the lowballing of PHEV CO2 output enabled several major carmaker groups to avoid over €5bn in penalties from 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs would pay approximately €500 more annually in operating costs than would be assumed under laboratory conditions.

“The bold statements that automakers often promote about their PHEV vehicles are clearly far from the truth,” stated a transport expert. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving costs. In reality, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of energy consumption, CO₂ production, and operating costs.”

Policy Debate and Automotive Pressure

Plug-in hybrid vehicles have recently been brought again into policy debates as automakers have pressed the European Union to relax CO₂ targets. A proposed ban on new combustion engine cars in 2035 has faced intense pressure from the automotive sector and opposition from EU countries with large automotive manufacturing.

Some senior politicians have suggested plug-in hybrids as a possible “compromise” option to introduce in the legislation.

One external energy policy specialist, who was not involved with the study, described the report a “very useful contribution” after a long period in which parts of the automotive sector claimed there was too little data to accurately evaluate real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in lab and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” they said. “Any regulatory adjustments regarding PHEVs should be implemented with utmost caution and considering this evidence.”