LEZs in the following countries require action before you enter the zone. For all the schemes below, one Sticker is valid for each country (or in the case of Bolzano Province region)
In Austria; in windscreen stickers are increasingly needed in the Austrian LEZs. Stickers are required for Vienna and Niederösterreich, and are likely to be required in other Austrian LEZs soon. In LEZs where a sticker is not yet required, you need to show your vehicle papers in a traffic check.
In Germany a windscreen sticker is required for all vehicles in all German LEZs. Stickers [plakette in German] can be bought from garages, testing stations [TÜV], the LEZ city administration, or online, for example from TÜV-Nord in several languages.
In the Netherlands, Dutch vehicles are registered through the national database.
In London, British vehicles (not Northern Irish, Channel Island etc) are registered through the national vehicle database. Other vehicles, not on this database:
need to register separately. Registration makes sure that the authorities have the information on which vehickes comply.
In Sweden vehicles with exemptions need to have a windscreen sticker.
In Prague you will need a windscreen sticker (likely to be able to be either a Czech or German one) once the LEZ starts.
For the Mont Blanc Tunnel, the price depends on the Euro standard. This is controlled manually at the toll point, Euro standard is estimated by the age of the vehicle.