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Plug-in hybrid cars produce nearly five times more planet-heating pollution than lab-reported figures show, as per a recent analysis.

Growing Gap In Official and Real-World CO2 Output

Statistics reveals that PHEVs emit just one-fifth less CO₂ than traditional petrol and diesel vehicles, according to analysis carried out by a non-profit group. That differs significantly with laboratory estimates, which assumed a 75% decrease in pollution.

Researchers examined data from in-vehicle energy use meters of 800,000 cars sold in Europe from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, up from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported figures are falling,” stated a senior researcher participating in the report. “That gap is widening and poses a serious problem. Consequently, PHEVs emit nearly as much as petrol vehicles.”

Primary Factors Driving the Emissions Gap

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in battery power compared to total mileage. They determined that just 27% of travel was completed in EV mode, while lab estimates suggested 84%.

Additionally, when running in electric mode, pollution amounts were well above official projections. This happened because EV motors were not strong sufficient to function alone, resulting to combustion motors using gasoline for nearly a third of the travel completed in electric mode.

Regulatory and Financial Consequences

Based on calculations, the lowballing of PHEV CO2 output allowed several large automaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would pay about €500 more per year in running costs than would be assumed under lab tests.

“The bold claims that manufacturers often promote about their PHEV vehicles are obviously far from the truth,” commented a transport analyst. “Buyers are being misled into thinking that by buying a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are only slightly better than regular gas and diesel cars in terms of energy use, CO₂ production, and running expenses.”

Policy Discussion and Industry Lobbying

Plug-in hybrid cars have recently been drawn again into political discussions as automakers have lobbied the EU to weaken CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the car industry and opposition from EU countries with significant car manufacturing.

Several senior politicians have suggested plug-in hybrids as a potential “compromise” solution to include in the legislation.

An independent energy economics specialist, who was not involved with the study, described the report a “very useful addition” after a long period in which parts of the automotive industry argued there was insufficient information to properly evaluate actual CO2 output.

“The results demonstrate, beyond any doubt, that the gap between lab and real-world PHEV energy use and CO₂ output is much, much larger than for petrol or diesel cars,” the expert stated. “All policy changes regarding PHEVs should be implemented with utmost care and in the light of that data.”