Many passing motorists honked their car horns in support.
Some surprised motorists honked their horns and gave their 10-peso toll - about $1.75 - to the protesters in a sign of solidarity.
Irritated motorists honked at them, while others looked on curiously.
Across the city, motorists honked horns to show support, creating an enormous din that lasted for more than an hour in some places.
Here, Manzullo and others ask motorists to honk their horns if they are tired of sitting in traffic congestion.
Although the protesters, then about 2,500 strong, slowed traffic, some motorists honked their horns in support.
As I sped past them on the inside, stationary motorists honked angrily.
The streets are clean, free of graffiti and litter; motorists, except for the occasional surly outsider, rarely honk their horns.
Henry Morgan once joked that a careful motorist honks his horn as he goes through a red light.
Some motorists have honked in approval adding to the noise level.