[Dinoguy1000]

Depending where in the US you look, the price of gas has done anything from less than doubling to increasing more than five-fold over the past decade.* It's not $8/gallon, but there are definitely places where you'd have to pay $4-6 per gallon, and it's only becoming more widespread. If there's one thing US citizens have shown, though, it's that they're perfectly willing to continue shelling out more and more money to drive ridiculously inefficient vehicles, even while they grumble about the spiraling price and (depending where you look) speak of mythical, massive reserves of oil the US supposedly has that could last the US anywhere from decades to centuries, depending who you ask.

Simply adding more costs onto gas is going to do nothing more to change what the average US citizen drives then what the past decade of price increases have.

* This is based on anecdote and recollection; I don't have any sources to back it up, but if it's wrong one way or the other, more than likely it's conservative.

[runako]

This doesn't really match with the data collected in the 2007-2008 price spike. While the price of oil was peaking, US drivers demonstrated that they will change their behavior somewhere on the curve. Notably, miles driven started dropping well before the recession hit. I'm not sure what the breakpoint was, but I believe it was around $4/gallon. (Yes, gas cost much more in some places and is still above $4 now, but the relevant number is the national average, currently about $3.60).

So you're right that the rise in prices from ~$0.90 in 1999 to multiples of that do not impact demand significantly. However, there is a threshold above which American drivers will react.