Plug-in hybrids, marketed as a bridge to zero-emission transport, are under intense scrutiny as new data reveals their real-world emissions are six times higher than advertised. A 2026 Fraunhofer Institute study found these vehicles consume almost six liters of fuel per 100 kilometers on average, 300 percent more than stated in their official EU type-approval certification. This discrepancy occurs because the cars still consume an average of three liters per 100 kilometers even when operating primarily on electric power.
The environmental organization Transport & Environment (T&E) reports that the actual CO₂ emissions of plug-in hybrids average 145 grams per kilometer, compared to the 24 grams per kilometer measured in the WLTP tests. Plug-in hybrids are one of the biggest greenwashing tricks of the automotive industry
, says Lucien Mathieu of T&E. Additionally, they are a rip-off for consumers who end up paying far more for fuel than they expected.
A Boom for Automakers, a Challenge for Regulators
Despite the criticism, plug-in hybrids are booming. They are considered more environmentally friendly than pure combustion engines and hybrids without plugs. For automakers, these models are a windfall, as they lower fleet CO₂ emissions on paper and generate higher profits than pure electric cars. The EU is currently reviewing whether to allow plug-in hybrids to remain on the market even after 2035, prompting environmentalists to call for stricter criteria to ensure they make a genuine contribution to CO₂ reduction.
Proposed Criteria for “Well-Designed” Plug-in Hybrids
T&E has proposed four key criteria in a report to the EU for promoting “well-designed” plug-in hybrid models:
- The electric motor must be at least three times as powerful as the combustion engine to ensure the vehicle operates purely electrically under all real-world conditions.
- Mandatory DC fast-charging capability (over 100 kW) to encourage drivers to recharge the battery quickly while on the go.
- A maximum fuel tank volume of 15 liters, incentivizing the use of electric power.
- An electric range of at least 200 km by 2030, with the vehicle required to operate in a 0-g/km mode when the battery is not empty (EV-priority mode).
Uncertain Future for EU Regulations
It remains unclear whether the EU will incorporate these proposals into its upcoming CO₂ regulations, which are under review. The call for a smaller fuel tank has drawn particular criticism in some conservative media. The debate highlights a fundamental question: can plug-in hybrids be designed to deliver on their environmental promises, or will they continue to fall short in practice?
