Men arguing over who's is smallest?
For each individual the cost-benefit analysis will obviously differ. There is no one price barrier. Economic disorder occurs when the price of an 'essential' such as energy rises suddenly and disproportionatley in relation to most peoples' incomes. Sudden readajustment is often painful if not crippling.
The best way for societies to prepare for a continuous price rise in petrol would be to raise taxes on it now. The full cost of it should be in the price and then some. People would alter their lives and locations accordingly over a reasonable period of time and would not be so prone to financial ruin. Once long distance car/air travel prices people out of their jobs they will have to sell-up and move closer to work. The prices of such property will fall. Prices of city housing will rise. A 100 mile round trip to a Walmart will make it an expensive place to buy food as opposed to a walk to the citymart on one's own block etc etc.
At the moment, petrol prices in the USA are absurdly low and bear no relation to the true cost. Pollution, climate change, resource wars, foreign policy, the costs of maintaining world stability in the Middle East, road deaths and injuries, health costs, distorted pricing in food markets and so on should all be laid onto the cost of petrol.
There is little doubt that, the way things are structured in the USA at the moment, the average Joe over there will be hurt more than the average John here, in the UK by, say, a quadrupling of petrol prices. We travel less because the country is tiny. The stupid thing is, we are increasingly following your trend towards out of town shopping, moves to the country entailing longer commutes etc.
By the way, on the macho thing, mine's about half a metre!
(I walk down two floors to my office

).