The German government is about to clear the way for the country’s local cities to legally drive older diesel cars off the road. And it’s not the first time German cities have moved to put the squeeze on older vehicles.

At the beginning of 2008, a number of German cities and towns started to institute what were called low-emission ‘Umwelt’ Zones. To access these areas, your vehicle needed to have an engine with a Euro 4 pollution rating.

Euro 4 cars got a green sticker for the windscreen, Euro 3 and Euro 2 cars got a yellow and red sticker, respectively.

According to the website dedicated to ‘Environmental’ Zones, the latest was brought in on the 1 April this year at Marburg, bringing the number up to 53, with 51 of them demanding a green sticker.

However, after ‘dieselgate’ became global news last year, governments and campaigners have had to admit that obsessing over CO2 emissions - a harmless gas locally, and one much appreciated by trees - had led European cities into the far more serious problem of the toxic pollution emitted by ‘low CO2’ diesel engines.