Perhaps you would like to alert your readers to a potential trap. Recently, in Hanover, parked up legally in the museum area, I returned to find a ticket on the car. On enquiry, this turned out to be a ticket for entering the 'Umwelt Zone'. Penalty: one point and a 40 Euros fine. I should have had a windscreen a badge, to confirm the car's emissions were acceptable for entry. This one-off badge costs around 5 Euros at the appropriate main dealer in return for sight of the car's documents. It is unlikely that an old diesel or petrol car without a 'cat' would be acceptable. A foreign plate is no excuse for ignorance, although the information is very well concealed on the Hanover website. Without a badge you are supposed to park and ride into town. Even worse, this is now being extended even to quite small towns in Bavaria, and already applies to most of the large cities in the western half of Germany.