🔗 Share this article

Plug-in hybrid cars release nearly five times more planet-heating emissions than lab-reported data indicate, as per a new report.

Growing Gap Between Official and Real-World Emissions

Data shows that PHEVs emit only 19% less CO₂ than traditional petrol and diesel cars, according to analysis conducted by a advocacy group. That contrasts sharply with laboratory tests, which assumed a three-quarters reduction in pollution.

Researchers studied information from in-vehicle energy use meters of 800,000 vehicles sold in the EU from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, increased from 3.5 times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” stated a senior analyst involved in the report. “This discrepancy is widening and poses a significant issue. Consequently, PHEVs pollute almost as much as petrol cars.”

Primary Factors Driving the Emissions Gap

Analysts attributed most of the gap to overestimates of the “electric driving share” – the percentage of kilometers travelled in battery power compared to total mileage. They found that just 27% of driving was done in electric mode, while official assumptions assumed over four-fifths.

Even, when operating in electric mode, emission levels were significantly higher than lab projections. This occurred because EV motors were insufficiently powerful enough to operate alone, leading to engines using fossil fuels for almost a third of the travel covered in electric mode.

Regulatory and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output enabled four major automaker companies to avoid over €5bn in penalties between 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs could pay about €500 more annually in running expenses than is assumed under laboratory conditions.

“The strong statements that automakers often promote about their PHEV cars are obviously way off the truth,” commented a transport expert. “Consumers are being misled into believing that by buying a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are little improved than regular petrol and diesel vehicles in terms of energy use, CO₂ emissions, and running costs.”

Policy Debate and Industry Pressure

Plug-in hybrid cars have lately been brought again into policy debates as automakers have lobbied the European Union to weaken CO₂ targets. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the car sector and opposition from member states with large automotive industries.

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

One external energy economics specialist, who was not involved with the research, called the report a “very useful contribution” after years in which segments of the automotive industry argued there was too little data to properly evaluate actual CO2 output.

“The results show, without question, that the gap between lab and real-world PHEV fuel consumption and CO₂ output is significantly larger than for petrol or conventional vehicles,” the expert stated. “Any regulatory changes concerning PHEVs should be implemented with utmost care and considering that data.”