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Plug-in hybrid cars produce almost five times more planet-heating emissions than official figures show, as per a recent analysis.

Widening Gap In Lab and Real-World CO2 Output

Data shows that PHEVs release only one-fifth less CO₂ than conventional petrol and diesel cars, based on research carried out by a advocacy organization. This differs significantly with laboratory tests, which suggested a 75% reduction in pollution.

Analysts examined information from onboard fuel consumption monitors of 800,000 vehicles sold in Europe between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, up from three and a half times in 2021.

“Actual CO2 output are increasing, while official figures are decreasing,” stated a lead analyst participating in the report. “This gap is widening and creates a significant problem. As a result, PHEVs pollute nearly as much as gasoline cars.”

Primary Factors Driving the Emissions Gap

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the ratio of miles travelled in electric mode compared to total distance. They found that just a quarter of driving was done in electric mode, whereas lab estimates suggested over four-fifths.

Even, when running in electric mode, pollution levels were well above official estimates. This occurred because EV motors were not strong enough to function independently, leading to engines burning gasoline for almost a third of the travel completed in electric mode.

Regulatory and Economic Implications

Based on estimates, the underestimation of PHEV CO2 output allowed four large carmaker companies to escape over €5bn in fines between 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs would pay approximately €500 more annually in running expenses than is estimated under laboratory conditions.

“The strong statements that manufacturers often promote about their PHEV cars are clearly way off the truth,” stated a transport expert. “Buyers are being misled into thinking that by buying a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are little improved 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 drawn back into political debates as automakers have pressed the EU to weaken CO₂ targets. A proposed prohibition on new internal combustion cars in 2035 has faced heavy lobbying from the car industry and resistance from EU countries with large automotive industries.

Some high-level officials have suggested PHEVs as a possible “flexibility” solution to introduce in the legislation.

An external energy policy specialist, who was not involved with the research, called the report a “very useful contribution” after a long period in which parts of the automotive industry argued there was insufficient information to accurately assess real-world CO2 output.

“These findings show, beyond any doubt, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or conventional vehicles,” they said. “All policy adjustments regarding PHEVs should be made with extreme caution and considering that evidence.”