Germany has launched a scheme to retrofit its diesel public buses with exhaust-scrubbing systems, and introduce charging points to encourage drivers to switch to e-cars. Still, environmentalists say that's not enough. They want all diesel vehicles — including private cars — retrofitted, or taken off the road.

Milan, one of Italy's most polluted cities, has banned cars from its downtown area during certain hours. Other cities in Italy and abroad have experimented with similar schemes, for example permitting only cars with odd or even license plates on the road at given times in order to limit the amount of traffic.

The Macedonian capital of Skopje is battling with pollution levels up to 15 higher than permitted by the EU — though it's not yet a member state, so isn't facing fines. Macedonia's smog problem is largely down to burning coal and emissions from aging, inefficient industry and vehicles. To get people to leave their dirty old cars at home, the government has introduced free public transport.

One street in London exceeded the EU's annual nitrogen dioxide limit on January 30 — less than a month into 2018. Actually, this is an improvement — it's the first time in a decade the British capital has kept within the annual limit for more than six days. Mayor of London Sadiq Khan has announced he wants to alert the city's schools on days when pollution is particularly bad.

The reputation of Germany's famed carmakers may have taken a hit, but their sales still soar. Yet German brands make up less than two-thirds of all cars on German roads, which is still a male-dominated territory: Only one-third of all owners in 2017 were women. Interestingly, that number has virtually not changed over the past decade.

German passenger vehicles, are growing steadily older, from 8.1 years a decade ago to 9.3 years in 2017, the highest-ever age. By the way: By no means is Germany the car capital of the world: It ranks 20th in motor vehicles per capita - 17 spots behind the US, where every 10 people own eight cars. The world's least motorized country? Togo.

Roughly 600,000 vehicles - 13 percent of all cars on German roads - are considered vintage cars which means they are more than three decades old. 380,000 have a historic license plate, which requires the vehicle to be in "contemporary, original preservable condition."

As of January 1, 2017, 45.8 million passenger vehicles were registered in Germany. Based on a population of 82.8 million, it translates to 684 cars per 1,000 people. Today, there are five times as many cars in Germany than there were half a century ago when roughly 9 million vehicles drove on the "Autobahn."

The average passenger vehicle age in Germany varies from state to state. Maybe not surprisingly, cars in Bavaria, the home of BMW and the state with the highest economic per capita output, are the youngest at nine years, while the average vehicle on Brandenburg's roads, the state surrounding Berlin, is almost a decade old.

While the number of gasoline-powered cars have remained remarkably stable over the past decade, their share steadily decreased to two-thirds of all engines in 2017. The number of diesel cars has risen from 10 to 15 million since 2008. Electric and hybrid cars combined made up 200,000 of all 45 million - that's 0.5 percent. In Norway, the share of electric vehicles alone is more than 1 percent.