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

In Germany, environmental zones (Umweltzonen) are established to reduce air pollution. Vehicles that enter these zones must display a specific sticker indicating their emission standards.

The particulate matter sticker system categorizes vehicles based on their emissions. Predominantly, petrol engines (choice 1) can sometimes qualify for a sticker depending on their age and emissions, diesel engines (choice 2) are specific in requiring stickers due to their higher emissions, and electric motors (choice 3) are typically exempt from requiring a sticker since they produce no tailpipe emissions.

Therefore, understanding that all three options represent types of vehicles subject to the regulations is important. Petra engines may qualify, diesel engines usually require a sticker, and while electric motors are exempt, they are included to depict the full spectrum of vehicles governed under these traffic regulations.