Paris does have Fußgängerzonen as well (around Les Halles for example, in La Defance, Latin Quarter ...) but this is a huge city. Only Berlin comes close, and there are cars all around Potsdamer Platz, Brandenburger Tor, Ku'Damm ... But I agree, Paris would clearly benefit from a no car zone from Rivoli to maybe Luxemburg. The roads are too small for serious car traffic anyway.