The European Commission is examining the measure as part of a broader push to curb real-world transport emissions.
Why Brussels is Targeting Hybrid Fuel Tanks
The core issue driving the debate stems from a stark gap between official laboratory test results and everyday driving habits. According to a report by the environmental organization Transport & Environment (T&E), real-world carbon dioxide emissions from plug-in hybrids registered in the European Union in 2024 ran nearly six times higher than official figures indicated. While laboratory testing suggested an 83 percent reduction in emissions compared to traditional combustion engines, the actual real-world benefit hovered at roughly 14 percent.
Data compiled by the organization shows that drivers cover only 27 percent of their mileage using electric power alone. Many motorists rarely plug in their vehicles after purchase, treating them essentially as conventional gasoline cars while continuing to haul the deadweight of heavy lithium-ion battery packs.
To break this pattern, T&E proposed reducing standard plug-in hybrid fuel tanks from an industry average of roughly 51 liters down to a maximum of 15 liters. Operating under a realistic consumption rate of 6.7 liters per 100 kilometers, a 15-liter tank would limit internal combustion range to approximately 220 kilometers. Drivers who refuse to charge their batteries would find themselves forced to make nearly 57 fuel stops annually, up from the current average of roughly 17.
Broader Regulatory Ripple Effects Across the Fleet
Beyond plug-in hybrids, a strict 15-liter cap could sweep in other vehicle categories depending on how regulators draft the final rules. Large luxury sedans like the Audi A8, which features an 82-liter diesel tank, or imported Chinese models like the Yangwang U8 equipped with 75-liter capacities, could face direct disruption. Several automakers have previously expanded fuel tank volumes precisely to help meet corporate average emissions targets—a compliance pathway that a strict capacity ceiling would eliminate.
At the same time, Asian competitors continue marketing vehicles boasting large fuel tanks and combined driving ranges exceeding 1,200 kilometers. This design philosophy contrasts sharply with the European Commission’s focus on battery dependence. Meanwhile, the broader transition to zero-emission vehicles remains politically contentious. Governments in France and Germany have pushed for greater regulatory flexibility, advocating space for efficient hybrids and renewable fuels ahead of the bloc’s target date for new combustion vehicle sales.
Market Realities and the Existing Vehicle Population
Market adoption statistics show changing market conditions for new vehicle registrations across the European Union. During the first nine months of 2026, pure battery-electric vehicles climbed to 22.7 percent of new car registrations, totaling 1.93 million units and overtaking traditional gasoline cars, which slipped to 21.2 percent. Plug-in hybrids accounted for 10.1 percent of the new market.
Yet the composition of vehicles currently on European roads tells a fundamentally different story. Eurostat data indicates that by the end of 2025, the EU counted 7.6 million registered battery-electric passenger cars—representing a single-digit share of a total fleet exceeding 260 million vehicles. The vast majority of drivers continue to rely on conventional gasoline or diesel engines.
