People wouldn't use publicly-owned cars, they would used publicly-owned buses, trams, subways, and other forms of mass transit, plus (as the article points out)

People wouldn't use publicly-owned cars, they would used publicly-owned buses, trams, subways, and other forms of mass transit, plus (as the article points out), making it easier to walk or bike. I believe the goal of limiting car use in Paris is as part of re-designing the city so it can be lived in without having to use cars, yes.