What cars that are driven within designated environmental zones must display a particulate matter sticker?

In German environmental zones (Umweltzonen), vehicles must display a particulate matter sticker (Feinstaubplakette) to show their emissions category. This applies not only to diesel engines but also petrol engines and electric vehicles. Petrol engines produce less particulate matter but still require a sticker to verify compliance. Electric vehicles typically receive a special sticker that allows them access, reflecting their low emissions. The sticker system helps control air pollution by restricting access for high-emission vehicles. Therefore, all cars—petrol, diesel, and electric—driven within these zones must have the appropriate sticker displayed.