Plug in Hybrid Cars Pollute Almost as Much as Gasoline Vehicles, Study Finds

PHEVs release nearly 5x greater global warming pollution than official data indicate, according to a new analysis.

Growing Gap In Lab and Real-World Emissions

Data reveals that PHEVs emit just one-fifth lower CO₂ than conventional gas and diesel cars, based on research conducted by a non-profit group. That differs sharply with laboratory estimates, which assumed a three-quarters reduction in pollution.

Analysts examined information from in-vehicle fuel consumption monitors of 800,000 vehicles sold in Europe between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, increased from 3.5 times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” stated a lead researcher involved in the report. “This gap is growing and poses a significant problem. As a result, PHEVs pollute nearly as much as gasoline cars.”

Primary Reasons Behind the Discrepancy

Analysts linked most of the difference to overestimates of the “electric driving share” – the percentage of kilometers travelled in electric mode compared to overall distance. The team found that just a quarter of driving was completed in electric mode, whereas lab assumptions assumed 84%.

Additionally, when operating in electric mode, pollution amounts were well above official estimates. This occurred because electric motors were insufficiently powerful enough to operate independently, resulting to engines using fossil fuels for almost a third of the travel covered in EV mode.

Policy and Financial Consequences

According to estimates, the lowballing of PHEV CO2 output enabled four large carmaker groups to escape over €5bn in fines between 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs would pay about €500 more annually in operating costs than would be assumed under laboratory tests.

“The strong claims that manufacturers often promote about their PHEV vehicles are clearly way off the mark,” commented a automotive expert. “Buyers are being misled into believing that by buying a PHEV, they are helping the planet and cutting money. Actually, PHEVs are little improved than regular petrol and diesel cars in terms of fuel use, CO₂ production, and operating costs.”

Policy Debate and Automotive Lobbying

Hybrid cars have lately been drawn again into political debates as automakers have lobbied the European Union to relax CO₂ standards. A planned prohibition on new internal combustion cars in 2035 has faced intense pressure from the car sector and resistance from EU countries with significant automotive industries.

Some high-level officials have proposed plug-in hybrids as a possible “compromise” option to introduce in the regulation.

One external energy policy expert, who was not involved with the research, called the report a “highly valuable contribution” after a long period in which parts of the car sector argued there was insufficient information to accurately evaluate real-world emissions.

“The results demonstrate, beyond any doubt, that the gap in official and actual PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or conventional cars,” they stated. “Any policy changes concerning PHEVs should be made with utmost care and in the light of this data.”