What happens when a city bans cars from its streets?

What happens when a city bans cars from its streets?
bbc.com

Automobiles are dangerous, kill thousands of people every year, contribute significantly to pollution, and cause health problems by discouraging physical activity. They're expensive, inefficient, and cause more harm than good within major cities IMO.

My dream is that one day most streets in Manhattan will be closed to car traffic and replaced with green space full of trees, flowers, children playing, and usable public space.

I live for several years in a medium sized wealthy Western European city that's clogged with traffic. Why?

Well, rich Europeans don't like living in cities with tall ugly blocks a so they grow outwards by developing cozy low density suburbs.

1) This suburban expansion was possible due to the cheap automobiles that permitted pretty much everyone to move outside of the cities and away from their jobs, where they could find properties they could afford, outside of the coverage of the rail network. It's almost impossible now, when everyone outside of the city is dependent on their cars to get to work/supermarket/city, to get them to leave their cars without first implementing a massive public transport network that would be too expensive to run profitably so it's much cheaper for the cities to just let people have their cars as they're the ones bearing the cost instead of the city.

2) It's also heavily political. The party that so much as dares to touch drivers and their cars will commit political suicide. Especially since my city is wealthy due to the extensive automotive industry nearby (R&D and manufacturing). Whenever politicians here propose less cars on the road, the auto industry threatens with lost jobs and jobs are way more important for a politician's career than people in the city dying prematurely of air pollution. And not to mention all the dealerships and service centers that contribute to political campaigns and public events especially in smaller cities.

I'd love to see cars banned from this beautiful city, but seeing how culturally attached the locals are to their cars and suburban lifestyle, I'm afraid it's just a pipe dream at this point.

What are you supposed to do if you like to take trips to places hundreds of miles away? What if your job involves visiting many different locations in your city throughout the day?

I have family that lives in the same city as me and the difference between visiting them via public transport and using a car is 3 hours vs 40 minutes. This is also NYC which is considered a model city for public transport.

Think of it this way: whatever the cost to society of cheap and plentiful public transport it will be a small fraction of the cost of car based transportation.

Parking, the cost of producing and maintaining the vehicles themselves, the pollution , the accidents, it all really adds up.