I was thinking about this today as I bimbled in to work.
I think Critical Mass has it the wrong way around. Instead of a mass of cyclists, we need a mass of cars.
Once a year, everyone who normally commutes or otherwise uses a bike as day to day transport should get hold of a car and drive instead. For those who can't drive, as many as possible get a taxi.
The aim is to demonstrate that people who chose to cycle are not slowing traffic down, they reduce congestion. People on bikes benefit everyone, even drivers. To reinforce this anyone who would normally be on a bike would display a large bike graphic in their back window.
In itself that won't encourage anyone to ride a bike, but it would encourage the habitual drivers to think of bikes as a good thing for other people at least. And just that acceptance would make a real difference both to how cyclists are treated today and to whether people think of cycling as a viable way of getting around in future.
Really, when you think about it like that we should be the WMV's best friend for helping to keep his roads clear