Treehugger mocks this, from the notoriously hack-a-rrific Wall Street Journal editorial page:

Petroleum not consumed by Prius owners is not “saved”. It does not stay in the ground. It is consumed by someone else. Greenhouse gases are still released.

I’m all for mocking the WSJ editorial page, but this statement is quite true. Oil supply and demand are tightly coupled right now and are only going to get more so. Any dribble of oil you don’t use will be snapped up by someone else — perhaps one of the growing legion of Chinese drivers — and so on and on until the remaining oil becomes prohibitively expensive and forces the market to provide alternatives.

It would be nice to think that environmental sentiment could free the world from oil, but it’ll never happen.

If your goal is to save money or save oil, buying a Prius should be far down your list.

Buy a Prius, if you like, to express your values and make a statement to manufacturers that there’s a market for these kinds of cars.

But let’s not let the hybrid hype get out of hand.