Scott Lemieux asked a very good question in the comments a couple of posts ago:
"Roughly what percentage of energy consumption is taken up by the internal combustion engine, and what by energy production? The higher the latter, the more difficult the long-term problems (of peak oil) would seem to me, although perhaps it doesn't really matter much."
The first part of my answer comes from an interview with T. Boone Pickens who started Mesa Petroleum Company in 1956 with a $2,500 investment and built it into the largest independent oil and gas company in America and now runs one of the largest energy hedge funds. T. Boone does a nice job of explaining why he thinks we are at the tipping point. (In fact, today he had a couple of quotes about oil testing $70/bbl soon and a couple of other related topics. He's been right so far.)
"Let me tell you some facts the way I see it. Global oil (production) is 84 million barrels (a day). I don't believe you can get it any more than 84 million barrels. I don't care what (Saudi Crown Prince) Abdullah, (Russian Premier Vladimir) Putin or anybody else says about oil reserves or production. I think they are on decline in the biggest oil fields in the world today and I know what's it like once you turn the corner and start declining, it's a tread mill that you just can't keep up with. So, when you start adding the reserves in these countries, you're not even replacing what you're taking out..."