Point of it was to minimize the amount of respirable dust and ozone in the inner-city air. Reasoning: older cars not later equipped with catalysts or other filters put out more than newer cars, and thus should not be aloud to come into inner city limits, were air-flow and exchange is limited due to all the buildings.
Who gave Munich the authority to do this? The Germany state. It gave all the big cities the authority to do this, and it is not only Munich that took advantage. Berlin, Frankfurt, Hamburg, Cologne, Nuremberg...
What does it cost the Bavarians? To get a badge for your car, (depending on what kind of car you have, these are green, yellow, red) costs from 5 to 8 Euros. It does not expire.
As to how much the signs cost that have to be put up to show where the "inner city" starts, and how much it is to put them up - no one knows.
As to if it is a good idea: Take it up with them again. People have tried to fight it, but as you see, it's in effect. It's been some time since the first cities started it, and already the first papers say that there is no difference in the amount of respirable matter and ozone in the air, compared to before the badges and zones were in effect.
On the other hand: Never trust a statistic that you haven't done yourself. Those things can express what you want if you want it enough, so...
