Paris' Car-free Day isn't going so well these days. This year it had to compete with, of all things, a huge auto show, and there's evidence that the event is stalling:
[T]he car-free day introduced in 1998 by the then-Socialist government is in decline. In 2002, 98 French cities and towns participated. Last year, it was 72. This year, there will only be 50.
The organisers say that is because September 22 falls in the middle of the week, posing a problem for authorities trying to balance economic and transport necessities and raising the possibility that the day might be moved to a Sunday from next year.
It does seem that it would be easier to go without a car on days when you don't have to, for example, GO TO WORK. Perhaps Paris could simply change the even to Car-free Night, and everyone could protest the car while they're fast asleep.
Of course, Parisians don't really hate cars. They use them all the time. Here's the author of the Paris Area Railway Master Plan:
Because of its ability to bring you from your starting point to your destination without having to walk, wait, or change vehicles, the car saves time. In the Paris suburbs, it usually saves you more than half an hour per trip, compared with public transport, despite the existence of perhaps the best public transport network in the world.
In central Paris, movement by car also saves time, but not as significantly as in other parts of the region. Central city residents often choose public transport because parking is difficult to find and too costly.
In French provincial cities and the Paris suburbs, the only ones who use public transport are those who don't have another option.