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Plug-in hybrid cars emit almost 5x more planet-heating pollution than lab-reported data indicate, as per a recent report.

Widening Gap In Lab and Real-World Emissions

Statistics shows that PHEVs emit just one-fifth less CO₂ than traditional gas and diesel cars, according to research carried out by a advocacy group. That contrasts sharply with laboratory tests, which suggested a 75% reduction in emissions.

Researchers examined information from in-vehicle fuel consumption monitors of 800,000 cars registered in Europe between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official emissions are falling,” said a lead analyst involved in the study. “That discrepancy is widening and poses a serious problem. Consequently, PHEVs pollute nearly as much as petrol vehicles.”

Key Factors Driving the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in battery power compared to overall distance. The team determined that only a quarter of driving was completed in electric mode, whereas lab assumptions suggested over four-fifths.

Additionally, when operating in EV mode, emission amounts were well above official estimates. This occurred because electric motors were insufficiently powerful sufficient to operate independently, leading to engines burning gasoline for almost one-third of the travel covered in EV mode.

Regulatory and Financial Consequences

Based on calculations, the underestimation of PHEV CO2 output enabled several large automaker companies to escape over €5bn in penalties between 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could pay approximately €500 extra annually in operating expenses than is estimated under lab tests.

“The strong claims that automakers often promote about their plug-in hybrid cars are clearly way off the truth,” commented a automotive expert. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the planet and cutting money. In reality, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of fuel use, CO₂ production, and operating costs.”

Political Debate and Industry Pressure

Hybrid cars have recently been brought back into policy discussions as automakers have lobbied the European Union to weaken CO₂ standards. A proposed ban on new combustion engine cars in 2035 has faced intense pressure from the car industry and resistance from member states with large car industries.

Some senior politicians have proposed plug-in hybrids as a possible “flexibility” solution to include in the legislation.

An external energy economics expert, who was not involved with the study, described the report a “highly valuable contribution” after years in which segments of the car sector claimed there was too little data to properly evaluate real-world CO2 output.

“The results show, without question, that the gap in official and real-world PHEV fuel consumption and CO₂ output is significantly larger than for petrol or conventional cars,” they stated. “Any regulatory adjustments concerning PHEVs should be implemented with utmost caution and considering this data.”