Here's a NY Times headline that helps crystallize the difference between the Democratic candidates:
As Gas Costs Soar, Buyers Flock to Small Cars

Clinton has joined her friend and well-known economic dunderhead John McCain by supporting a gas tax holiday in response to high fuel prices.  This is a plan-- okay, political gimmick-- that will not only do nothing to address the root cause of high energy prices but will actually encourage the same destructive status quo careless consumption that created to this crisis in the first place. For good measure, the uncollected tax will create a funding shortfall for critical services like infrastructure maintenance and, worst of all, retard market forces that, for once, are actually doing us good.

The switch to smaller, more fuel-efficient vehicles has been building in recent years, but has accelerated recently with the advent of $3.50-a-gallon gas. At the same time, sales of pickup trucks and large sport utility vehicles have dropped sharply.

Here's the reality: not only will gas prices remain high they actually should be high.  Oil is an increasingly limited resource in growing demand.  That's a simple enough economic equation for even John McCain to understand. (He, of course, doesn't.)
For the good of our economy and our environment, America needs to turn the page on rampant consumption of fossil fuels.  There will be some sacrifice and "life-style changes" necessary to do this.  And it will require continued market pressure from high fuel prices and active leadership from our government.  And clearly there is only one candidate who understands that: Barack Obama.