What motor vehicles may enter an environment zone that has this sign?

In this context, the sign indicates an environmental zone (Umweltzone) where specific regulations apply to motor vehicles to reduce air pollution.

Permitted vehicles include those with a green particulate emissions sticker, which signifies that they meet stringent emissions standards. Additionally, motorcycles are allowed entry into this zone. German regulations specify that vehicles that fulfill the conditions for having a green sticker, even without such a sticker present, may also enter the zone.

This combination of requirements ensures that only vehicles with low emissions can access these environmentally sensitive areas, helping to improve air quality in urban environments. Being aware of these rules is crucial for compliance and to avoid fines.