A good sort of chain letter - and cheaper petrol?

A good idea passed on by Roley Flutey:

By now you're probably thinking petrol priced at about $1.50 is super cheap. It is currently $1.90 for regular unleaded. And now that the oil companies and OPEC have conditioned us to think that the cost of a gallon of gas is cheap at $1.50, we need to take aggressive action to teach them that buyers control the marketplace.
-----The only way we are going to see the price of petrol come down is if we hit them in the pocket by not purchasing their petrol! And, we can do that without hurting ourselves.
-----How? Since we all rely on our cars, we can't just stop buying petrol. But we can have an impact on petrol prices if we all act together to force a price war.

Here's the idea:
For the rest of this year, don't purchase any petrol from the two biggest global petroleum companies, ExxonMobil and Shell.
-----If they are not selling any petrol, they will be inclined to reduce their prices. If they reduce their prices, the other companies will have to follow suit.
-----But to have an impact, we need to reach literally millions of Mobil and Shell petrol buyers. And it's really simple to do! This post goes to 320 people (including you) who could each send it to ten more people. Get your pencil and paper to work - oh, go on then, use your calculator - to find out how easily and quickly two million consumers have been informed.
-----Now - how soon to reach TWO HUNDRED MILLION people - worldwide?
-----Again, to make it happen, all you have to do is send this to ten people. That's all!
-----How long would all that take? If each of us sends this email out to ten more people within one day of receipt 200,000,000 people could conceivably be contacted worldwide within the next eight days!
-----By acting together, we can make a difference. If this makes sense to you, please pass this message on and boycott Mobil and Shell until they lower their prices below the $1.50 range and keep them down.
-----OK, you might have to break the habit of a lifetime by passing Shell and Mobil, but it's their pocket or yours.