Well, as we're seeing now, the cost of everything is going up. My wife tells me every week about groceries.
So, I believe.....if gas does hit the $5.00 a gal mark, the entire economy could collapse. (If that happens we may all be looking to hunt our hole!

) It will hurt every type of business imaginable. Airlines, hotels, groceries, shipping etc.
People will not go anywhwere outside of say...20 miles or so. They just won't be able to afford it.
Now, if you're rich and can afford it, cool, I'm happy for you. You worked hard to earn it so you won't feel it. (Too much....anyway)
Another thing, IF, the entire country boycotted just one gas/oil company say...BP, I mean NO ONE buy gas from them, then it wouldn't be long until BP dropped their price for fuel. And when they did, everyone would go buy gas from them. The other companies (the ones you went to during the boycott) would then drop their prices also to get their customer back.
Also, consider this, a barrel of oil is 42 gallons. (NOT 55 gals!) At say (today) it's $104.00 a barrel, gas here in Atlanta is $3.49 a gal. That means the gas company, investors, ie: speculators etc. have $2.47 a gal in that barrel. That's a $1.02 profit for them. However, Ga. tax is 25 cents a gal so the oil company's/investors profit is 77 cents.
In reference to Aunti M, she's correct, basically due to the fact that investors retreated from the falling real estate and global stock markets, they diverted their funds to oil futures. This sudden surge has driven up oil prices as well.
Plus, you have developing nations like China, India, Pakistan, and Indonesia consuming also. Like us, they're not going to stop consuming anytime soon.
I could go on about lack of refineries, weather catastrophies etc. but I think everyone gets the picture.
Finally, there is plenty of oil here in the US. IF, we uncapped and started using OUR OWN oil, and get off foreign oil, you would see prices go down in the Mid East. Why? Because of supply and demand. They'd have plenty of supply and no demand, thus they'd lower their price. BUT, we have to start using our oil here first to have that kind of leverage.
My apologies for going on so long.

I poked it with a stick..........