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Plug-in hybrid cars produce almost 5x more planet-heating pollution than lab-reported figures show, according to a recent analysis.

Growing Discrepancy Between Lab and Actual CO2 Output

Statistics reveals that PHEVs emit only 19% lower CO₂ than conventional gas and diesel vehicles, according to research conducted by a advocacy organization. That contrasts significantly with lab tests, which assumed a three-quarters decrease in emissions.

Researchers examined information from in-vehicle energy use meters of 800,000 cars registered in the EU between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, increased from 3.5 times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” stated a senior analyst involved in the study. “That gap is widening and poses a serious problem. As a result, PHEVs emit almost as heavily as gasoline vehicles.”

Key Reasons Driving the Emissions Gap

Researchers attributed most of the gap to inflated estimates of the “utility factor” – the ratio of kilometers travelled in electric power compared to overall distance. They determined that only a quarter of driving was completed in electric mode, while lab assumptions assumed over four-fifths.

Additionally, when operating in electric mode, pollution amounts were well above official projections. This happened because electric motors were insufficiently powerful sufficient to function alone, leading to combustion motors using gasoline for nearly one-third of the travel covered in EV mode.

Regulatory and Financial Implications

According to calculations, the underestimation of PHEV emissions allowed four large carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs would spend about €500 more annually in operating expenses than is estimated under lab tests.

“The strong statements that automakers like to make about their plug-in hybrid cars are clearly far from the mark,” commented a automotive expert. “Consumers are being duped into thinking that by buying 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 emissions, and running expenses.”

Political Debate and Automotive Lobbying

Plug-in hybrid cars have recently been drawn again into policy debates as carmakers have lobbied the European Union to weaken CO₂ targets. A planned prohibition on new combustion engine cars in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with large automotive manufacturing.

Several high-level officials have suggested plug-in hybrids as a potential “flexibility” solution to introduce in the legislation.

An independent energy economics specialist, who was not involved with the study, called the report a “highly valuable contribution” after a long period in which parts of the automotive sector argued there was too little data to properly evaluate real-world emissions.

“These findings demonstrate, beyond any doubt, that the gap between lab and real-world PHEV energy use and CO₂ output is much, much larger than for gasoline or conventional cars,” they stated. “Any policy adjustments concerning PHEVs should be made with extreme caution and in the light of that data.”