From the Daily News:
The mayor said it is now "completely clear that congestion pricing has the strong backing of the people of New York City."
No, it was more likely due to this:
The vote came after months of intense lobbying by Quinn and Bloomberg, who has wined and dined council members at Gracie Mansion. Critics say he has tried to win votes by dangling construction projects and endorsements in front of council members.
The Wonkster has a complete breakdown of who the April Fools were.