Where do you draw the line?

Yes, I am really hoping for comments/discussion on this post. Otherwise, it's just me talking to cyberspace.

So, I mentioned in my Going Green post this article, which gives 10 reasons to be happy about higher petrol (gasoline-- I call it petrol, to distinguish it in my mind from natural gas, which we also have to pay for), and then I read this post, predicting the potential dire consequences of Sen. Obama's proposed solution to high petrol prices. (Please don't use my comments section to comment on his post-- if you want to comment on the post, comment at his blog. Thanks.)

So I read the post, and thought, "I wouldn't drive if petrol were at $10 a gallon." Then I realised, I would probably stop driving before we got to that point. But I am not sure where my line is. So I put it before Chad: "At what price per gallon for petrol do you say to me, 'Honey, we're going to park the car until the price of petrol comes back down.'?"

In the course of the ensuing discussion, I said that I am almost to that point now; in fact, after filling up our tiny car for $40 yesterday, I am now wondering whether we can run all our errands on Thursdays, when I already have to drive anyway. (I can't take the bike to prayer group and still make it to work on time afterwards.) Chad says yes, we can, and I absolutely agree.

So, the final verdict? I think my line is somewhere around $5.50 per gallon. Certainly, we arrive at it by $6.

Where is your line? At what point do you park your car and pursue "alternative" transportation?