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PHEVs emit almost 5x more global warming emissions than lab-reported data show, as per a new analysis.

Growing Discrepancy Between Lab and Actual CO2 Output

Statistics reveals that PHEVs emit only 19% lower CO₂ than conventional gas and diesel cars, based on analysis conducted by a advocacy group. This contrasts sharply with laboratory tests, which suggested a three-quarters reduction in emissions.

Researchers examined data from onboard fuel consumption monitors of 800,000 cars sold in the EU between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, up from 3.5 times in 2021.

“Real-world emissions are rising, while official emissions are decreasing,” said a senior analyst involved in the study. “That gap is widening and creates a significant problem. Consequently, PHEVs pollute almost as heavily as petrol vehicles.”

Primary Factors Driving the Emissions Gap

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers driven in electric mode compared to overall mileage. The team found that only a quarter of travel was completed in electric mode, while official assumptions suggested 84%.

Even, when running in electric mode, pollution amounts were well above official projections. That occurred because electric motors were insufficiently powerful enough to function independently, leading to engines using fossil fuels for almost one-third of the distance completed in electric mode.

Regulatory and Financial Consequences

According to calculations, the underestimation of PHEV CO2 output allowed several major carmaker groups to escape more than €5bn in penalties between 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 more per year in operating costs than is estimated under lab tests.

“The bold claims that manufacturers often promote about their plug-in hybrid cars are clearly far from the mark,” stated a automotive expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are only slightly better than regular gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating expenses.”

Policy Discussion and Automotive Pressure

Hybrid vehicles have lately been brought back into political discussions as carmakers have pressed the European Union to weaken CO₂ targets. A planned ban on new internal combustion vehicles in 2035 has faced intense pressure from the automotive sector and resistance from EU countries with large car manufacturing.

Several senior politicians have proposed PHEVs as a possible “compromise” solution to include in the legislation.

An independent energy economics expert, who was not involved with the study, called the report a “very useful addition” after years in which parts of the automotive sector claimed there was too little data to properly evaluate real-world emissions.

“The results show, beyond any doubt, that the gap in lab and actual PHEV energy use and CO₂ emissions is significantly larger than for gasoline or conventional vehicles,” they stated. “All policy changes regarding PHEVs should be made with extreme care and in the light of that evidence.”