As of this month a low emission zone started in Aachen. The start of this new emission zone means that all diesel vehicles without a ‘so-called’ closed loop catalytic converter (a device that controls emissions), must have a sticker. The image below shows the area where the new emission is affective since the first of February, it covers 25 km2:
Be aware that a ‘LEZ sticker’ must be bought when entering with a vehicle that does not comply to the environmental regulations, the costs of these are roughly between 6 EUR and 13 EUR. The penalty without driving with such a sticker is 80 EUR.
For more information on different toll systems go to: https://www.dkv-euroservice.com/gb/services/toll/toll-services-by-country/.