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PHEVs emit nearly 5x greater planet-heating emissions than lab-reported figures indicate, according to a recent analysis.

Widening Discrepancy In Official and Actual Emissions

Statistics shows that PHEVs release just 19% lower CO₂ than traditional gas and diesel cars, according to analysis conducted by a non-profit group. This contrasts significantly with lab tests, which assumed a three-quarters reduction in emissions.

Researchers examined data from onboard energy use meters of 800,000 cars registered in Europe from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official estimates, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while official emissions are falling,” stated a lead researcher involved in the study. “That discrepancy is growing and poses a significant problem. Consequently, PHEVs emit almost as heavily as petrol cars.”

Key Reasons Driving the Emissions Gap

Analysts attributed most of the difference to overestimates of the “utility factor” – the percentage of kilometers travelled in battery power compared to overall distance. They determined that only a quarter of driving was completed in electric mode, while official estimates assumed over four-fifths.

Even, when operating in EV mode, emission amounts were well above lab estimates. This occurred because EV motors were not strong enough to function independently, leading to engines burning fossil fuels for nearly one-third of the distance completed in EV mode.

Policy and Financial Consequences

Based on calculations, the underestimation of PHEV emissions enabled four major automaker groups to avoid over €5bn in fines between 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs would pay about €500 extra per year in running expenses than would be estimated under lab conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid cars are clearly far from the truth,” stated a automotive expert. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Political Debate and Automotive Pressure

Plug-in hybrid cars have recently been drawn again into policy debates as carmakers have pressed the European Union to relax CO₂ targets. A planned ban on sales of new internal combustion cars in 2035 has faced heavy pressure from the car industry and resistance from EU countries with significant automotive industries.

Some senior officials have proposed PHEVs as a possible “flexibility” solution to include in the regulation.

One external energy economics specialist, who was not involved with the study, called the analysis a “highly valuable addition” after years in which parts of the car sector argued there was too little information to accurately evaluate real-world emissions.

“These findings demonstrate, beyond any doubt, that the difference between official and real-world PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or diesel cars,” the expert said. “All regulatory adjustments concerning PHEVs should be made with utmost care and in the light of that evidence.”