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Plug-in hybrid electric vehicles produce nearly five times greater global warming pollution than official data indicate, according to a recent analysis.

Growing Gap In Lab and Real-World Emissions

Statistics shows that PHEVs release just 19% less CO₂ than conventional petrol and diesel vehicles, based on analysis conducted by a non-profit group. This contrasts significantly with lab estimates, which suggested a three-quarters reduction in pollution.

Researchers studied information from onboard energy use meters of 800,000 vehicles sold in the EU between 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, up from three and a half times in 2021.

“Actual CO2 output are increasing, while official emissions are falling,” stated a senior analyst involved in the study. “That gap is widening and creates a significant issue. Consequently, PHEVs emit nearly as much as gasoline vehicles.”

Primary Factors Driving the Discrepancy

Analysts linked the majority of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in electric power compared to total distance. They determined that just 27% of driving was done in electric mode, while official assumptions suggested over four-fifths.

Even, when operating in EV mode, pollution levels were significantly higher than lab estimates. This happened because electric motors were not strong enough to operate alone, leading to engines burning fossil fuels for almost a third of the travel covered in EV mode.

Policy and Financial Implications

Based on estimates, the underestimation of PHEV CO2 output enabled several large automaker companies to avoid over €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could pay about €500 more annually in operating expenses than is assumed under laboratory conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid vehicles are clearly far from the truth,” stated a automotive analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are little improved than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and operating costs.”

Policy Debate and Automotive Lobbying

Plug-in hybrid vehicles have recently been brought back into policy debates as carmakers have lobbied the European Union to relax CO₂ standards. A proposed ban on new combustion engine cars in 2035 has faced heavy lobbying from the car industry and resistance from EU countries with significant car industries.

Several high-level politicians have proposed PHEVs as a possible “flexibility” option to include in the legislation.

One external energy economics expert, who was not involved with the research, called the analysis a “very useful addition” after years in which segments of the automotive sector argued there was insufficient data to accurately assess real-world emissions.

“These findings demonstrate, without question, that the gap in official and actual PHEV fuel consumption and CO₂ output is significantly larger than for petrol or conventional cars,” the expert stated. “All policy changes regarding PHEVs should be made with extreme care and in the light of this evidence.”