What would $4 gas mean to you?

We all know it's coming. We read the headlines about $100 oil, and hear talk about how oil prices are closely-tied to the market at the moment, and we think, any day now.

Some analysts say it'll never happen. The man on the street is getting cynical. Indeed, a survey released yesterday reveals that a vast majority of Americans, 71%, think we'll see $4/gallon gasoline come summer.

How would $4 gas effect you? The first and most obvious would be to dramatically impact the kind of car you drive.