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Plug-in hybrid electric vehicles release nearly 5x more global warming pollution than official data indicate, as per a new report.

Widening Discrepancy In Lab and Actual CO2 Output

Statistics reveals that PHEVs release just 19% lower CO₂ than traditional petrol and diesel vehicles, according to research conducted by a advocacy organization. This contrasts sharply with laboratory tests, which assumed a three-quarters reduction in emissions.

Analysts examined data from onboard fuel consumption monitors of eight hundred thousand cars sold in Europe from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are decreasing,” said a senior analyst involved in the study. “That discrepancy is growing and creates a significant issue. As a result, PHEVs pollute almost as much as petrol vehicles.”

Primary Factors Behind the Emissions Gap

Analysts attributed the majority of the gap to overestimates of the “utility factor” – the percentage of kilometers driven in electric mode compared to total distance. The team found that just a quarter of driving was done in EV mode, while lab estimates assumed over four-fifths.

Additionally, when operating in electric mode, pollution amounts were significantly higher than lab projections. This happened because electric motors were not strong enough to operate independently, resulting to engines burning gasoline for nearly one-third of the travel covered in electric mode.

Policy and Economic Implications

According to estimates, the lowballing of PHEV CO2 output allowed four major carmaker groups to escape more than €5bn in penalties from 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ targets.

Furthermore, drivers of PHEVs could pay about €500 more per year in running costs than is assumed under laboratory conditions.

“The bold claims that manufacturers often promote about their plug-in hybrid vehicles are clearly way off the mark,” commented a automotive analyst. “Buyers are being duped into believing that by buying a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are little improved than standard gas and diesel cars in terms of fuel consumption, CO₂ production, and operating costs.”

Policy Debate and Industry Lobbying

Plug-in hybrid cars have lately been drawn back into policy debates as carmakers have pressed the EU to relax CO₂ standards. A proposed ban on new internal combustion vehicles in 2035 has faced intense lobbying from the automotive sector and resistance from member states with large car manufacturing.

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

One independent energy policy specialist, who was unaffiliated with the study, called the report a “very useful contribution” after years in which parts of the automotive industry argued there was insufficient data to properly assess actual emissions.

“These findings demonstrate, without question, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or conventional vehicles,” they stated. “Any regulatory changes regarding PHEVs should be made with utmost care and considering that data.”