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PHEVs emit almost five times greater global warming emissions than official data indicate, as per a new analysis.

Widening Discrepancy Between Official and Real-World CO2 Output

Data reveals that PHEVs release just one-fifth lower CO₂ than traditional gas and diesel vehicles, according to research conducted by a advocacy organization. This contrasts significantly with laboratory tests, which suggested a three-quarters reduction in pollution.

Researchers examined information from in-vehicle fuel consumption monitors of 800,000 cars sold in the EU from 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are decreasing,” stated a lead researcher participating in the report. “This discrepancy is widening and poses a significant issue. Consequently, PHEVs pollute almost as heavily as petrol vehicles.”

Primary Reasons Driving the Emissions Gap

Analysts attributed the majority of the difference to overestimates of the “utility factor” – the percentage of miles travelled in battery mode compared to overall mileage. The team found that only a quarter of driving was completed in EV mode, whereas lab assumptions assumed over four-fifths.

Additionally, when operating in electric mode, emission amounts were well above lab estimates. That happened because electric motors were insufficiently powerful sufficient to function alone, resulting to engines using gasoline for nearly a third of the travel covered in electric mode.

Policy and Financial Implications

According to calculations, the underestimation of PHEV CO2 output enabled four large carmaker groups to escape over €5bn in penalties between 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could spend about €500 more annually in operating expenses than would be assumed under lab tests.

“The bold claims that manufacturers like to make about their plug-in hybrid cars are clearly way off the truth,” commented a transport expert. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the environment and saving money. Actually, PHEVs are little better than regular petrol and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Policy Discussion and Industry Lobbying

Hybrid cars have recently been brought again into policy debates as carmakers have pressed the EU to weaken CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the car sector and resistance from member states with significant automotive industries.

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

One independent energy economics specialist, who was not involved with the research, described the report a “highly valuable contribution” after years in which parts of the car industry claimed there was insufficient information to properly assess actual CO2 output.

“The results demonstrate, beyond any doubt, that the difference in lab and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional cars,” the expert said. “All policy changes concerning PHEVs should be made with extreme care and in the light of this data.”