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PHEVs emit nearly 5x greater global warming pollution than lab-reported figures show, as per a new report.

Widening Gap In Lab and Actual CO2 Output

Statistics shows that PHEVs release only one-fifth lower CO₂ than traditional petrol and diesel vehicles, according to analysis conducted by a advocacy organization. This contrasts significantly with laboratory tests, which assumed a 75% decrease in pollution.

Researchers studied information from onboard fuel consumption monitors of 800,000 cars sold in the EU from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while official figures are decreasing,” stated a senior researcher involved in the study. “This gap is widening and creates a serious issue. As a result, PHEVs pollute almost as heavily as gasoline cars.”

Primary Reasons Driving the Discrepancy

Analysts attributed the majority of the gap to inflated estimates of the “utility factor” – the percentage of miles driven in battery mode relative to overall distance. The team determined that only 27% of driving was done in EV mode, whereas lab assumptions assumed 84%.

Additionally, when running in electric mode, emission levels were well above lab estimates. That happened because EV motors were insufficiently powerful enough to operate independently, resulting to combustion motors using gasoline for nearly a third of the distance completed in electric mode.

Regulatory and Economic Consequences

Based on calculations, the underestimation of PHEV CO2 output enabled several large automaker companies to escape more than €5bn in penalties from 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ targets.

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

“The strong claims that automakers like to make about their plug-in hybrid vehicles are clearly way off the mark,” commented a transport analyst. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are only slightly better than regular gas and diesel vehicles in terms of fuel use, CO₂ production, and running costs.”

Political Debate and Industry Lobbying

Plug-in hybrid cars have recently been drawn back into policy discussions as carmakers have pressed the EU to relax CO₂ targets. A proposed prohibition on new combustion engine cars in 2035 has faced heavy lobbying from the automotive industry and resistance from member states with significant automotive industries.

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

An independent energy economics expert, who was not involved with the study, described the report a “highly valuable contribution” after years in which parts of the automotive sector claimed there was too little data to accurately assess actual CO2 output.

“These findings show, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ emissions is much, much larger than for gasoline or conventional vehicles,” the expert stated. “All regulatory changes concerning PHEVs should be made with extreme care and in the light of that evidence.”