The stat I saw was that the total fuel that evaporates from Car fuel tanks via the breathers exceeds total consumption of 100LL across the whole of Europe.
This statement is completely incorrect, as petrol-powered vehicles have had totally-enclosed fuel systems since the early 1970's to prevent excessive fuel evaporation losses.
The system is called Evaporative Vapour Emission Control (EVAP) and is one of the earliest emission control systems fitted to petrol-powered vehicles.
The primary vapour control device is a charcoal-filled canister that is fitted either in the engine bay, or close to the fuel tank.
Howstuffworks.com - Evaporative Emission Control System