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Plug-in hybrid electric vehicles produce nearly 5x more planet-heating emissions than official figures indicate, as per a recent analysis.

Widening Discrepancy Between Lab and Actual CO2 Output

Statistics reveals that PHEVs emit just one-fifth lower CO₂ than conventional gas and diesel vehicles, based on research carried out by a advocacy organization. This contrasts significantly with laboratory estimates, which suggested a 75% decrease in emissions.

Researchers examined information from onboard energy use monitors of 800,000 cars registered in the EU from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while official figures are decreasing,” stated a senior researcher participating in the report. “This discrepancy is widening and poses a significant problem. Consequently, PHEVs emit nearly as heavily as petrol vehicles.”

Primary Reasons Behind the Emissions Gap

Analysts attributed most of the gap to inflated estimates of the “utility factor” – the ratio of miles driven in battery power compared to total mileage. The team determined that only a quarter of travel was completed in electric mode, while official assumptions assumed 84%.

Additionally, when running in EV mode, emission levels were well above official projections. That happened because electric motors were not strong enough to operate independently, resulting to combustion motors burning gasoline for almost one-third of the distance covered in EV mode.

Policy and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output enabled four major carmaker companies to escape over €5bn in fines from 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs could spend approximately €500 more annually in operating costs than is estimated under lab tests.

“The bold claims that automakers often promote about their PHEV vehicles are obviously far from the truth,” stated a automotive analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the planet and cutting money. Actually, PHEVs are little better than standard gas and diesel vehicles in terms of energy consumption, CO₂ production, and operating costs.”

Policy Discussion and Automotive Pressure

Plug-in hybrid vehicles have lately been drawn back into policy discussions as carmakers have lobbied the EU to weaken CO₂ targets. A planned prohibition on sales of new combustion engine cars in 2035 has faced intense pressure from the automotive industry and resistance from EU countries with significant car industries.

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

One external energy economics expert, who was not involved with the research, called the report a “highly valuable addition” after a long period in which segments of the automotive industry argued there was too little data to accurately assess real-world emissions.

“The results show, beyond any doubt, that the difference between official and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or diesel cars,” they stated. “All regulatory changes concerning PHEVs should be made with extreme caution and considering this data.”