I was discussing this with a coworker yesterday, and we calculated the impact to his wallet if gasoline was to go to $4.00/gallon. He drives a pickup truck and his wife drives an SUV... each gets around 17MPG. And they drive everywhere... I don't think that the oil ever gets cool in the engines of their cars.

At $4.00/gallon, they would spend about $700 - $800 a month on gasoline alone... and when you add car payments it gets worse. The two of them will be spending in the neighborhood of $1600 every month just to support their current driving lifestyle.

But you know what? It isn't enough to change their habits. He refuses to drive anything smaller than his mega truck. They will not inconvenience themselves to carpool. They'll whine a bit and keep on driving...